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Factors influencing preference of insulin regimen in people with type 1 (insulin–dependent) diabetes1
Diabetes Research and Clinical Practice 39 (1998) 23 – 29
Factors influencing preference of insulin regimen in people with type 1 (insulin – dependent) diabetes1 P. Perros a,*, I.J. Deary b, B.M. Frier a b
a Department of Diabetes, Royal Infirmary, Edinburgh, UK Department of Psychology, Uni6ersity of Edinburgh, Edinburgh, UK
Received 26 May 1997; received in revised form 3 October 1997; accepted 20 October 1997
Abstract The two commonest insulin regimens in current use in the UK are twice daily administration of short- and intermediate-acting insulins in combination, and soluble insulin before meals with intermediate-acting insulin at bed-time (basal-bolus regimen). A cross-sectional sample of patients with type 1 diabetes was studied using either a twice daily insulin regimen (n=30) or a basal-bolus regimen (n = 30), to assess their satisfaction with choice of insulin regimen and to examine the relationships between type of insulin regimen, personality, demographic variables and glycaemic control. Patients treated with a basal-bolus insulin regimen tended to be younger (P = 0.07), had an earlier onset of type 1 diabetes (P= 0.04), adjusted their dose of insulin more frequently (P =0.01), had received more secondary and further education (P=0.03), belonged to a higher socio-economic class, tended to be unmarried (P=0.07) and were less likely to be smokers (P= 0.03), than the group treated with twice daily administration of insulin. Current and previous glycaemic control assessed by glycated haemoglobin concentration, showed no correlation with type of insulin regimen, demographic data or personality variables. © 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Type 1 (insulin–dependent) diabetes mellitus; Insulin; Personality; Treatment satisfaction; Basal-bolus insulin regimen
1. Introduction * Corresponding author. Present address. Medical Unit 3, Freeman Hospital, Freeman Road, Newcastle upon Tyne NE7 7DN, UK. Tel.: +44 191 2843111, ext 26245; fax: + 44 0191 2131968. 1 Presented at the British Diabetic Association Spring Meeting, Harrogate, UK, 10 April 1997.
Good glycaemic control in people with type 1 diabetes helps to prevent diabetic complications [1], but usually requires strict long-term compliance with insulin therapy and diet, which many individuals find incompatible with their lifestyle.
0168-8227/98/$19.00 © 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S 0 1 6 8 - 8 2 2 7 ( 9 7 ) 0 0 1 0 9 - 5
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P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
People with type 1 diabetes are encouraged to assume responsibility for self-management of their diabetes, including the appropriate manipulation of their insulin therapy [2]. However, issues of patients’ satisfaction with their treatment and the impact of diabetes on quality of life must not be neglected [3]. The two principal insulin regimens that are currently most popular in the UK are twice daily mixtures of short- and intermediate-acting insulins (mainly soluble and isophane insulins in combination) and multiple injections of insulin (the basal-bolus regimen) with short-acting (soluble) insulin being administered before each meal, supplemented by an injection of intermediate- or long-acting insulin at bed-time. The basal-bolus insulin regimen allows flexibility in the timing of meals, at the expense of additional injections of insulin and more frequent self-monitoring of blood glucose to permit appropriate adjustment of the insulin dose [4]. This regimen is appreciated by patients whose activities vary significantly from day to day. However, the main determinants of the achievement of good glycaemic control are patient education, motivation and compliance, rather than the type of insulin regimen used. Psychological factors and personality traits are also considered to be important and may influence choice of insulin regimen and the quality of glycaemic control [5,6], although a study from this centre has not confirmed this premise [7]. The aim of the present study was to investigate the degree of patient satisfaction with their current insulin regimen and to examine the relationship between the type of insulin regimen and personality, demographic variables and quality of glycaemic control.
2. Materials and methods
2.1. Subjects Adult patients with type 1 diabetes were recruited from the out-patient clinics of the Department of Diabetes of the Royal Infirmary of Edinburgh, Scotland. Of those who attend the clinic, 1750 are type 1 diabetic patients, two thirds
of whom are treated with twice daily injections of insulin and a third with the basal-bolus regimen. It is the usual policy of this department to establish adults with newly diagnosed type 1 diabetes on a twice daily, combined insulin regimen, preferably with free-mixing of soluble and isophane insulins. Patients are informed subsequently of the availability of the basal-bolus insulin regimen and its suitability is assessed for the lifestyle of the individual subject. However, the decision to convert to a basal-bolus insulin regimen is delegated to the patient. Dietary recommendations for either insulin regimen consist of 50–55% of energy as complex carbohydrate, 15– 20 as protein and 30% as fat. Recommendations for frequency of home blood glucose monitoring are tailored to the individual. During periods of metabolic instability three pre-prandial measurements and a pre-bed-time measurement are the minimum recommended. In patients with stable and satisfactory glycaemic control once daily measurement (pre-prandially or at bed-time) in a staggered fashion is the minimum recommended frequency. Patients on basal-bolus insulin regimens are encouraged to test daily. Target blood glucose values are also individualised, but most patients are asked to achieve pre-prandial blood glucose concentrations of 5–8 mmol/l and HbA1 concentration of less than 9.5%. For the present study, exclusion criteria were age less than 18 or greater than 55 years, duration of diabetes less than 3 years and duration of use of current insulin regimen less than 1 year. The assignment of type 1 diabetes was based on clinical criteria (ketosis-prone diabetes in lean patients). Three patients declined to participate in the study and were excluded. Recruited to the regimen were 60 consecutive patients who satisfied the entry criteria and were being treated with a basal-bolus insulin regimen (n=30) or a twice daily combined insulin regimen (n= 30). All patients in the group using twice daily insulin were aware of the existence of the basal-bolus insulin regimen, but had chosen to remain on their current regimen. Information was gathered from patients during a structured interview which included their age, marital status, occupation (classified by a standard method as Class I; pro-
P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
fessional, class II; managerial, class III; skilled non-manual workers, class IV; partly skilled manual workers, class V; unskilled manual workers [8]), physical activity (graded: 1, sedentary; 2, moderate; 3, very active), smoking habit, number of years in full-time education (primary, secondary and further education), type of insulin regimen, frequency of home blood glucose monitoring, frequency of insulin dose adjustment and retrospective estimation of total number of episodes of severe hypoglycaemia (those requiring external assistance) in the previous 2 years. The study was approved by the local Medical Ethics Advisory Committee. Written informed consent was obtained before participating in the study.
2.2. Assessment of personality and satisfaction with treatment Patients were asked to complete two questionnaires: the Eysenck personality questionnaire-revised (EPQ-R) [9] and the diabetes treatment satisfaction questionnaire (DTSQ) [10]. The EPQR consists of 48 questions, with ‘yes’ or ‘no’ responses. This shortened form of the EPQ correlates well with the original EPQ [11] and is validated [7,12]. The extroversion scale ranges from extroversion to introversion, with the typical extrovert being sociable, has many friends, does not like reading or studying alone, is carefree, easy going, optimistic but loses his/her temper quickly and altogether does not keep his feelings under tight control. At the other extreme of this scale, the typical introvert is quiet, introspective, reserved and distant except to intimate friends, likes a well-ordered mode of life, keeps his/her feelings under close control and does not lose his temper easily. With regard to the neuroticism scale, the typically high neuroticism scorer is anxious, worries a lot, is moody, likely to sleep badly and is prone to suffer from a variety of psychosomatic disorders. The high neuroticism scorer is also overly emotional and these strong emotional reactions interfere with his proper adjustment, making him react in irrational and often rigid ways. At the other end of this scale the stable individual is unusually calm, even tempered, controlled and
25
unworried. The high psychoticism scorer can be described as being solitary, not caring for people, not fitting in anywhere, lacking in feeling and empathy, hostile to others and disregard for danger. These are all descriptions of individuals who are at the extremes of the different personality scales and most subjects score around the middle of the range for each of the personality variables. The EPQ-R provides measures of three personality dimensions and a fourth measure, which is a lie scale to determine whether or not the questions have been answered in a socially desirable way. The DTSQ is a questionnaire about the treatment of diabetes, with questions on fluctuations in blood glucose concentration, convenience and flexibility of treatment, satisfaction and readiness to continue with current treatment and happiness with their understanding of diabetes. Each question is graded from 1–6 with patients marking their satisfaction accordingly. If the questions concerning blood glucose concentrations are excluded, the remaining responses can be summated giving a total satisfaction score with a maximum value of 36. The DTSQ has been validated and shown to be a reliable measure of patient satisfaction [10] and its use has been recommended for assessment of psychological outcomes of diabetes care [13].
2.3. Assessment of glycaemic control Total glycated haemoglobin (HbA1) concentration was measured in venous or capillary blood, using high pressure liquid chromatography. The normal non-diabetic range for HbA1 was 5.5– 8.5% (2 S.D. below and above the mean). The current HbA1 concentration and the values obtained at the previous two annual review visits, were noted.
2.4. Statistics Mann-Whitney U and x 2 tests were used to compare the two groups of patients. Relationships between HbA1 as a measure of glycaemic control, insulin regimen, satisfaction with present insulin therapy and the demographic and personality variables were tested by Spearman correlation.
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P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
Table 1 Comparisons of demographic data and details of diabetic treatment with type of insulin regimen
Number of patients Median age in years (range) Sex (M/F) Median duration of type 1 diabetes in years (range) Median age at diagnosis in years (range) Marital Status (% married) Occupation (% professional) Smoking habits (% smokers) Median duration of full time education in years (range) Median total HbA1 concentration (%)(range) Frequency of home blood glucose monitoring expressed as median number of tests per week (range) Frequency of insulin dose adjustment expressed as median number per week (range) Frequency of severe hypoglycaemia in last 2 years expressed as median number of episodes (range)
3. Results Table 1 shows the demographic details and data relating to insulin therapy in the groups of patients receiving the two different insulin regimens. No differences were found between the two groups in sex ratio, duration of type 1 diabetes, HbA1 concentration, frequency of home blood glucose monitoring and estimated frequency of severe hypoglycaemia. Compared to the group treated with twice daily combined insulin therapy, the patients using the basal-bolus insulin regimen tended to be younger (median age 33.5 versus 44.5 years, P= 0.07) had an earlier onset of type 1 diabetes (median age at diagnosis 12.5 versus 25.5 years, P = 0.04), had received more full-time education (median 13 years versus 11.5 years, P = 0.03), belonged to a higher socio-economic class (proportion in social classes I and II 17.7 versus 3.3%, P =0.002), were less likely to be smokers (proportion smokers 10 versus 26.7%, P = 0.03), adjusted the dose of insulin more frequently (median frequency per week 1 versus 0, P =0.01) and fewer were married (proportion unmarried 36.7 versus 20%, P = 0.07). The relationships between type of insulin regimen, personality traits and satisfaction with dia-
Twice daily regimen
Basal-bolus regimen
P value
30 44.5 (26 – 55) 19/11 21.5 (3 – 39) 25.5 (4 – 44) 80 3.3 26.7 11.5 (9 – 21) 9.0 (7.2 – 14.5) 10 (2 – 30)
30 33.5 (19 – 54) 21/9 18.5 (3 – 34) 12.5 (2 – 42) 63.3 16.7 10 13.0 (10 – 20) 9.7 (7.6 – 14.4) 7 (0 – 30)
— 0.07 0.58 0.46 0.04 0.07 0.002 0.03 0.03 0.28 0.62
0 (0 – 3)
1 (0 – 8)
0.01
0 (0 – 14)
0 (0 – 30)
0.66
betic therapy are shown in Table 2. No significant differences between type of insulin regimen and personality measures were noted, suggesting that personality has no influence on the choice of insulin regimen. Satisfaction with diabetic treatment did not differ with the type of insulin regimen used. The relationships between HbA1 concentration, demographic data and personality variables are shown in Table 3. No significant correlations were found between HbA1 concentration and other variables, except for smokers who had a higher HbA1 concentration than non-smokers. The current total HbA1 concentration correlated closely with the average HbA1 in the previous 2 years, (r=0.8, PB0.001).
4. Discussion The present study has demonstrated a relationship between choice of insulin regimen by people with type 1 diabetes and various individual characteristics. The patients were selected at random from those attending an out-patient diabetes clinic and should therefore be representative of many patients with type 1 diabetes who receive regular
P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
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Table 2 Comparisons between type of insulin regimen, personality variables and satisfaction
Extroversion Score Neuroticism Score Psychoticism Score Satisfaction Score
Twice daily regimen
Basal-bolus regimen
P value
6.9 5.2 1.9 29.9
7.9 4.4 1.8 29.8
0.28 0.44 0.72 0.70
(3.5) (3.7) (2.1) (4.6)
(3.8) (3.2) (1.4) (4.6)
Data are presented as mean 9 S.D.
supervision in a specialist department. The patients who had elected to use the basal-bolus insulin regimen tended to be younger, unmarried, had shorter duration of diabetes, were better educated and were more likely to be non-smokers compared to patients taking twice daily therapy, administered as short and intermediate-acting insulins in combination. A similar level of satisfaction with their insulin treatment was declared by both groups of patients. This suggests that type 1 diabetic patients choose the insulin regimen that is most suited to their lifestyle, with flexibility of mealtimes being one of the key determinants for those individuals who lead a busy, varied and demanding professional and social life. A possible determinant of choice may be intellectual ability, as effective use of the basal-bolus insulin regimen requires more frequent decision-making regarding adjustment of insulin dose and this may be reflected by the greater experience of secondary and further education in this group. Older patients with a longer duration of type 1 diabetes may have a degree of resistance to changing to a new insulin regimen, especially those who have been long established on a conventional regimen of twice daily mixed insulins and this may partly explain group differences in age and duration of diabetes. In local clinical practice the basal-bolus insulin regimen had been advocated for not more than 8 years and its increasing usage with time may alter the demographic composition of this user group. Previous studies have shown that glycaemic control was improved when patients changed from a twice daily to a basal-bolus insulin regimen [4,14]. However, a common experience is that such improvement is not sustained by most pa-
tients [15] and the type of insulin regimen does not correlate with glycaemic control [16,17]. A recent survey of matched groups of patients with type 1 diabetes in this department indicated no difference in the quality of glycaemic control after 1 year of using either of these regimens [18]. In the present study, glycaemic control was similar in the two groups of patients as judged by the mean HbA1 concentration and the frequency of severe hypoglycaemia. This also confirms the clinical impression that conversion to a basal-bolus insulin regimen is not a panacea for improving glycaemic control. No relationships were found between personality variables, type of insulin regimen and HbA1 concentration. This suggests that personality variables are not good predictors of glycaemic control or choice of insulin regimen. Previous studies of personality type and glycaemic control in children and adults with type 1 diabetes have yielded conflicting results. Orlandini et al. [6] found that the ‘dramatic-dependent’ personality, akin to extroversion, had a significantly positive correlation with poor glycaemic control, while Gordon et al. [7] found an association between neuroticism and poor glycaemic control. Hepburn et al. [12] studied a large group of type 1 diabetic patients attending this department and found that personality was not a predictor of glycaemic control. Ziegler et al. [19] found that patients’ degree of practical knowledge about insulin adjustment did not correlate with implementation of dose modification or glycaemic control. At present, no reliable method exists for predicting the quality of glycaemic control which can be anticipated in individual diabetic patients.
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P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
Table 3 Relationships between demographic data, personality variables and recent total HbA1 concentration (Spearman correlation analysis, or Mann-Whitney U test) HbA1 concentration (mean 9 S.D.) Age
r Value 0.014
P value 0.92
Sex Male Female
9.7 (1.7) 9.7 (1.7)
0.90
Marital status Single Married
9.9 (1.3) 9.6 (1.8)
0.64
9.4 (1.4) 10.3 (2.1)
0.05
Smoking habits Non-smokers Smokers Activity Duration of education Occupation Age at onset of diabetes Duration of diabetes Extroversion Neuroticism Psychoticism
In conclusion, the present study has demonstrated that choice in favour of the multiple injection, basal-bolus insulin regimen over the more conventional twice daily, combined insulin regimen, was associated with a shorter duration of type 1 diabetes and a higher educational and professional status. Personality traits were not related to the choice of insulin regimen and similar levels of satisfaction with insulin therapy and quality of glycaemic control were evident with either insulin regimen.
Acknowledgements The authors wish to thank Mr S Ojo for collecting the data and the nursing staff of the Department of Diabetes of the Royal Infirmary of Edinburgh, for their co-operation with this study.
−0.134 −0.165 −0.078 0.014 −0.018 0.131 0.057 0.062
0.30 0.05 0.55 0.91 0.90 0.32 0.67 0.64
References [1] The Diabetes Control and Complications Research Group, The effects of intensive treatment of diabetes and the development and progression of long term complications in insulin dependent diabetes mellitus, New Engl. J. Med. 329 (1993) 977 – 986. [2] Workshop Report, Diabetes care and research in Europe: the Saint Vincent declaration, Diabetic Med. 7 (1990) 360. [3] C. Bradley, Assessing psychosocial outcomes associated with diabetes, Reducing Burden Diabetes 3 (1995) 8 – 10. [4] I.G. Jefferson, T.M. Marteau, M.A. Smith, J.D. Baum, A multiple injection regimen using an insulin injection pen and pre – filled cartridged soluble human insulin in adolescents with diabetes, Diabetic Med. 2 (1985) 493 – 497. [5] D. Giles, S. Strowig, P. Challis, P. Raskin, Personality traits as predictors of good diabetic control, J Diabetes Complicat. 6 (1992) 101 – 104. [6] A. Orlandini, M.R. Pastore, A. Fossati, S. Clerici, A. Sergi, A. Balini, M.A. Parlangeli, C. Maffei, A. Secchi, G. Pozza, Effects of personality on metabolic control in IDDM patients, Diabetes Care 18 (1995) 206 – 209.
P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29 [7] D. Gordon, S.G. Fisher, M. Wilson, E. Fergus, K.R. Paterson, C.G. Semple, Psychological factors and their relationship to diabetes control, Diabetic Med 10 (1993) 530 – 534. [8] Office of Population Censuses and Surveys,Classification of Occupations. London, HMSO Publication of the Government Statistical Service, 1980. [9] S.B.G. Eysenck, H.J. Eysenck, P.T. Barrett, A revised version of the psychoticism scale, Personal. Indiv. Differ. 6 (1985) 21 – 29. [10] C. Bradley, Handbook of Psychology and Diabetes: A Guide to Psychological Measurement in Diabetes Research and Practice, Harwood Academic, Chur, 1994. [11] H.J. Eysenck, S.B.G. Eysenck, Manual of the Eysenck Personality Questionnaire, Hodder and Stoughton, London, 1975. [12] D.A. Hepburn, S. Langan, I.J. Deary, K.M. MacLeod, B.M. Frier, Psychological and demographic correlates of glycaemic control in adult patients with type I diabetes, Diabetic Med. 11 (1994) 578–582. [13] C. Bradley, D.S. Gamsu, Guidelines for encouraging psychological well-being: report of a working group of the World Health Organization regional office for Europe and International Diabetes Federation European region
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[14]
[15]
[16]
[17]
[18]
[19]
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St Vincent Declaration Action Programme for Diabetes, Diabetic Med. 11 (1994) 510 – 516. N. Robinson, C.E. Lloyd, J.H Fuller, N.A. Yateman, Psychosocial factors and the onset of type I diabetes, Diabetic Med. 6 (1989) 53 – 58. D. Gordon, M. Wilson, K.R. Paterson, C.G. Semple, Audit of multiple insulin injection regimens in a large outpatient diabetic population, Diabetes Res. Clin. Pract. 17 (1993) 145 – 150. H.B. Mortensen, P. Hougaard, Comparison of metabolic control in a cross-sectional study of 2873 children and adolescents with IDDM from 18 countries, Diabetes Care 20 (1997) 714 – 720. H. Dorchy, M.P. Rogemans, D. Willems, Glycated hemoglobin and related factors in diabetic children and adolescents under 18 years of age: the Belgian experience, Diabetes Care 20 (1997) 2 – 6. A.J. Anwar, T. Farrell, B.M. Frier, Basal-bolus insulin regimens and diet in patients with insulin – dependent diabetes, Diabetic Med. 13 (Suppl 7) (1996) 522. O. Ziegler, M. Kolopp, J. Louis, A. Patris, G. Debry, P. Drouin, Self-monitoring of blood glucose and insulin dose alteration in type 1 diabetes mellitus, Diabetes Res. Clin. Pract. 21 (1993) 51 – 59.
Factors influencing preference of insulin regimen in people with type 1 (insulin – dependent) diabetes1 P. Perros a,*, I.J. Deary b, B.M. Frier a b
a Department of Diabetes, Royal Infirmary, Edinburgh, UK Department of Psychology, Uni6ersity of Edinburgh, Edinburgh, UK
Received 26 May 1997; received in revised form 3 October 1997; accepted 20 October 1997
Abstract The two commonest insulin regimens in current use in the UK are twice daily administration of short- and intermediate-acting insulins in combination, and soluble insulin before meals with intermediate-acting insulin at bed-time (basal-bolus regimen). A cross-sectional sample of patients with type 1 diabetes was studied using either a twice daily insulin regimen (n=30) or a basal-bolus regimen (n = 30), to assess their satisfaction with choice of insulin regimen and to examine the relationships between type of insulin regimen, personality, demographic variables and glycaemic control. Patients treated with a basal-bolus insulin regimen tended to be younger (P = 0.07), had an earlier onset of type 1 diabetes (P= 0.04), adjusted their dose of insulin more frequently (P =0.01), had received more secondary and further education (P=0.03), belonged to a higher socio-economic class, tended to be unmarried (P=0.07) and were less likely to be smokers (P= 0.03), than the group treated with twice daily administration of insulin. Current and previous glycaemic control assessed by glycated haemoglobin concentration, showed no correlation with type of insulin regimen, demographic data or personality variables. © 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Type 1 (insulin–dependent) diabetes mellitus; Insulin; Personality; Treatment satisfaction; Basal-bolus insulin regimen
1. Introduction * Corresponding author. Present address. Medical Unit 3, Freeman Hospital, Freeman Road, Newcastle upon Tyne NE7 7DN, UK. Tel.: +44 191 2843111, ext 26245; fax: + 44 0191 2131968. 1 Presented at the British Diabetic Association Spring Meeting, Harrogate, UK, 10 April 1997.
Good glycaemic control in people with type 1 diabetes helps to prevent diabetic complications [1], but usually requires strict long-term compliance with insulin therapy and diet, which many individuals find incompatible with their lifestyle.
0168-8227/98/$19.00 © 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S 0 1 6 8 - 8 2 2 7 ( 9 7 ) 0 0 1 0 9 - 5
24
P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
People with type 1 diabetes are encouraged to assume responsibility for self-management of their diabetes, including the appropriate manipulation of their insulin therapy [2]. However, issues of patients’ satisfaction with their treatment and the impact of diabetes on quality of life must not be neglected [3]. The two principal insulin regimens that are currently most popular in the UK are twice daily mixtures of short- and intermediate-acting insulins (mainly soluble and isophane insulins in combination) and multiple injections of insulin (the basal-bolus regimen) with short-acting (soluble) insulin being administered before each meal, supplemented by an injection of intermediate- or long-acting insulin at bed-time. The basal-bolus insulin regimen allows flexibility in the timing of meals, at the expense of additional injections of insulin and more frequent self-monitoring of blood glucose to permit appropriate adjustment of the insulin dose [4]. This regimen is appreciated by patients whose activities vary significantly from day to day. However, the main determinants of the achievement of good glycaemic control are patient education, motivation and compliance, rather than the type of insulin regimen used. Psychological factors and personality traits are also considered to be important and may influence choice of insulin regimen and the quality of glycaemic control [5,6], although a study from this centre has not confirmed this premise [7]. The aim of the present study was to investigate the degree of patient satisfaction with their current insulin regimen and to examine the relationship between the type of insulin regimen and personality, demographic variables and quality of glycaemic control.
2. Materials and methods
2.1. Subjects Adult patients with type 1 diabetes were recruited from the out-patient clinics of the Department of Diabetes of the Royal Infirmary of Edinburgh, Scotland. Of those who attend the clinic, 1750 are type 1 diabetic patients, two thirds
of whom are treated with twice daily injections of insulin and a third with the basal-bolus regimen. It is the usual policy of this department to establish adults with newly diagnosed type 1 diabetes on a twice daily, combined insulin regimen, preferably with free-mixing of soluble and isophane insulins. Patients are informed subsequently of the availability of the basal-bolus insulin regimen and its suitability is assessed for the lifestyle of the individual subject. However, the decision to convert to a basal-bolus insulin regimen is delegated to the patient. Dietary recommendations for either insulin regimen consist of 50–55% of energy as complex carbohydrate, 15– 20 as protein and 30% as fat. Recommendations for frequency of home blood glucose monitoring are tailored to the individual. During periods of metabolic instability three pre-prandial measurements and a pre-bed-time measurement are the minimum recommended. In patients with stable and satisfactory glycaemic control once daily measurement (pre-prandially or at bed-time) in a staggered fashion is the minimum recommended frequency. Patients on basal-bolus insulin regimens are encouraged to test daily. Target blood glucose values are also individualised, but most patients are asked to achieve pre-prandial blood glucose concentrations of 5–8 mmol/l and HbA1 concentration of less than 9.5%. For the present study, exclusion criteria were age less than 18 or greater than 55 years, duration of diabetes less than 3 years and duration of use of current insulin regimen less than 1 year. The assignment of type 1 diabetes was based on clinical criteria (ketosis-prone diabetes in lean patients). Three patients declined to participate in the study and were excluded. Recruited to the regimen were 60 consecutive patients who satisfied the entry criteria and were being treated with a basal-bolus insulin regimen (n=30) or a twice daily combined insulin regimen (n= 30). All patients in the group using twice daily insulin were aware of the existence of the basal-bolus insulin regimen, but had chosen to remain on their current regimen. Information was gathered from patients during a structured interview which included their age, marital status, occupation (classified by a standard method as Class I; pro-
P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
fessional, class II; managerial, class III; skilled non-manual workers, class IV; partly skilled manual workers, class V; unskilled manual workers [8]), physical activity (graded: 1, sedentary; 2, moderate; 3, very active), smoking habit, number of years in full-time education (primary, secondary and further education), type of insulin regimen, frequency of home blood glucose monitoring, frequency of insulin dose adjustment and retrospective estimation of total number of episodes of severe hypoglycaemia (those requiring external assistance) in the previous 2 years. The study was approved by the local Medical Ethics Advisory Committee. Written informed consent was obtained before participating in the study.
2.2. Assessment of personality and satisfaction with treatment Patients were asked to complete two questionnaires: the Eysenck personality questionnaire-revised (EPQ-R) [9] and the diabetes treatment satisfaction questionnaire (DTSQ) [10]. The EPQR consists of 48 questions, with ‘yes’ or ‘no’ responses. This shortened form of the EPQ correlates well with the original EPQ [11] and is validated [7,12]. The extroversion scale ranges from extroversion to introversion, with the typical extrovert being sociable, has many friends, does not like reading or studying alone, is carefree, easy going, optimistic but loses his/her temper quickly and altogether does not keep his feelings under tight control. At the other extreme of this scale, the typical introvert is quiet, introspective, reserved and distant except to intimate friends, likes a well-ordered mode of life, keeps his/her feelings under close control and does not lose his temper easily. With regard to the neuroticism scale, the typically high neuroticism scorer is anxious, worries a lot, is moody, likely to sleep badly and is prone to suffer from a variety of psychosomatic disorders. The high neuroticism scorer is also overly emotional and these strong emotional reactions interfere with his proper adjustment, making him react in irrational and often rigid ways. At the other end of this scale the stable individual is unusually calm, even tempered, controlled and
25
unworried. The high psychoticism scorer can be described as being solitary, not caring for people, not fitting in anywhere, lacking in feeling and empathy, hostile to others and disregard for danger. These are all descriptions of individuals who are at the extremes of the different personality scales and most subjects score around the middle of the range for each of the personality variables. The EPQ-R provides measures of three personality dimensions and a fourth measure, which is a lie scale to determine whether or not the questions have been answered in a socially desirable way. The DTSQ is a questionnaire about the treatment of diabetes, with questions on fluctuations in blood glucose concentration, convenience and flexibility of treatment, satisfaction and readiness to continue with current treatment and happiness with their understanding of diabetes. Each question is graded from 1–6 with patients marking their satisfaction accordingly. If the questions concerning blood glucose concentrations are excluded, the remaining responses can be summated giving a total satisfaction score with a maximum value of 36. The DTSQ has been validated and shown to be a reliable measure of patient satisfaction [10] and its use has been recommended for assessment of psychological outcomes of diabetes care [13].
2.3. Assessment of glycaemic control Total glycated haemoglobin (HbA1) concentration was measured in venous or capillary blood, using high pressure liquid chromatography. The normal non-diabetic range for HbA1 was 5.5– 8.5% (2 S.D. below and above the mean). The current HbA1 concentration and the values obtained at the previous two annual review visits, were noted.
2.4. Statistics Mann-Whitney U and x 2 tests were used to compare the two groups of patients. Relationships between HbA1 as a measure of glycaemic control, insulin regimen, satisfaction with present insulin therapy and the demographic and personality variables were tested by Spearman correlation.
26
P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
Table 1 Comparisons of demographic data and details of diabetic treatment with type of insulin regimen
Number of patients Median age in years (range) Sex (M/F) Median duration of type 1 diabetes in years (range) Median age at diagnosis in years (range) Marital Status (% married) Occupation (% professional) Smoking habits (% smokers) Median duration of full time education in years (range) Median total HbA1 concentration (%)(range) Frequency of home blood glucose monitoring expressed as median number of tests per week (range) Frequency of insulin dose adjustment expressed as median number per week (range) Frequency of severe hypoglycaemia in last 2 years expressed as median number of episodes (range)
3. Results Table 1 shows the demographic details and data relating to insulin therapy in the groups of patients receiving the two different insulin regimens. No differences were found between the two groups in sex ratio, duration of type 1 diabetes, HbA1 concentration, frequency of home blood glucose monitoring and estimated frequency of severe hypoglycaemia. Compared to the group treated with twice daily combined insulin therapy, the patients using the basal-bolus insulin regimen tended to be younger (median age 33.5 versus 44.5 years, P= 0.07) had an earlier onset of type 1 diabetes (median age at diagnosis 12.5 versus 25.5 years, P = 0.04), had received more full-time education (median 13 years versus 11.5 years, P = 0.03), belonged to a higher socio-economic class (proportion in social classes I and II 17.7 versus 3.3%, P =0.002), were less likely to be smokers (proportion smokers 10 versus 26.7%, P = 0.03), adjusted the dose of insulin more frequently (median frequency per week 1 versus 0, P =0.01) and fewer were married (proportion unmarried 36.7 versus 20%, P = 0.07). The relationships between type of insulin regimen, personality traits and satisfaction with dia-
Twice daily regimen
Basal-bolus regimen
P value
30 44.5 (26 – 55) 19/11 21.5 (3 – 39) 25.5 (4 – 44) 80 3.3 26.7 11.5 (9 – 21) 9.0 (7.2 – 14.5) 10 (2 – 30)
30 33.5 (19 – 54) 21/9 18.5 (3 – 34) 12.5 (2 – 42) 63.3 16.7 10 13.0 (10 – 20) 9.7 (7.6 – 14.4) 7 (0 – 30)
— 0.07 0.58 0.46 0.04 0.07 0.002 0.03 0.03 0.28 0.62
0 (0 – 3)
1 (0 – 8)
0.01
0 (0 – 14)
0 (0 – 30)
0.66
betic therapy are shown in Table 2. No significant differences between type of insulin regimen and personality measures were noted, suggesting that personality has no influence on the choice of insulin regimen. Satisfaction with diabetic treatment did not differ with the type of insulin regimen used. The relationships between HbA1 concentration, demographic data and personality variables are shown in Table 3. No significant correlations were found between HbA1 concentration and other variables, except for smokers who had a higher HbA1 concentration than non-smokers. The current total HbA1 concentration correlated closely with the average HbA1 in the previous 2 years, (r=0.8, PB0.001).
4. Discussion The present study has demonstrated a relationship between choice of insulin regimen by people with type 1 diabetes and various individual characteristics. The patients were selected at random from those attending an out-patient diabetes clinic and should therefore be representative of many patients with type 1 diabetes who receive regular
P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
27
Table 2 Comparisons between type of insulin regimen, personality variables and satisfaction
Extroversion Score Neuroticism Score Psychoticism Score Satisfaction Score
Twice daily regimen
Basal-bolus regimen
P value
6.9 5.2 1.9 29.9
7.9 4.4 1.8 29.8
0.28 0.44 0.72 0.70
(3.5) (3.7) (2.1) (4.6)
(3.8) (3.2) (1.4) (4.6)
Data are presented as mean 9 S.D.
supervision in a specialist department. The patients who had elected to use the basal-bolus insulin regimen tended to be younger, unmarried, had shorter duration of diabetes, were better educated and were more likely to be non-smokers compared to patients taking twice daily therapy, administered as short and intermediate-acting insulins in combination. A similar level of satisfaction with their insulin treatment was declared by both groups of patients. This suggests that type 1 diabetic patients choose the insulin regimen that is most suited to their lifestyle, with flexibility of mealtimes being one of the key determinants for those individuals who lead a busy, varied and demanding professional and social life. A possible determinant of choice may be intellectual ability, as effective use of the basal-bolus insulin regimen requires more frequent decision-making regarding adjustment of insulin dose and this may be reflected by the greater experience of secondary and further education in this group. Older patients with a longer duration of type 1 diabetes may have a degree of resistance to changing to a new insulin regimen, especially those who have been long established on a conventional regimen of twice daily mixed insulins and this may partly explain group differences in age and duration of diabetes. In local clinical practice the basal-bolus insulin regimen had been advocated for not more than 8 years and its increasing usage with time may alter the demographic composition of this user group. Previous studies have shown that glycaemic control was improved when patients changed from a twice daily to a basal-bolus insulin regimen [4,14]. However, a common experience is that such improvement is not sustained by most pa-
tients [15] and the type of insulin regimen does not correlate with glycaemic control [16,17]. A recent survey of matched groups of patients with type 1 diabetes in this department indicated no difference in the quality of glycaemic control after 1 year of using either of these regimens [18]. In the present study, glycaemic control was similar in the two groups of patients as judged by the mean HbA1 concentration and the frequency of severe hypoglycaemia. This also confirms the clinical impression that conversion to a basal-bolus insulin regimen is not a panacea for improving glycaemic control. No relationships were found between personality variables, type of insulin regimen and HbA1 concentration. This suggests that personality variables are not good predictors of glycaemic control or choice of insulin regimen. Previous studies of personality type and glycaemic control in children and adults with type 1 diabetes have yielded conflicting results. Orlandini et al. [6] found that the ‘dramatic-dependent’ personality, akin to extroversion, had a significantly positive correlation with poor glycaemic control, while Gordon et al. [7] found an association between neuroticism and poor glycaemic control. Hepburn et al. [12] studied a large group of type 1 diabetic patients attending this department and found that personality was not a predictor of glycaemic control. Ziegler et al. [19] found that patients’ degree of practical knowledge about insulin adjustment did not correlate with implementation of dose modification or glycaemic control. At present, no reliable method exists for predicting the quality of glycaemic control which can be anticipated in individual diabetic patients.
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P. Perros et al. / Diabetes Research and Clinical Practice 39 (1998) 23–29
Table 3 Relationships between demographic data, personality variables and recent total HbA1 concentration (Spearman correlation analysis, or Mann-Whitney U test) HbA1 concentration (mean 9 S.D.) Age
r Value 0.014
P value 0.92
Sex Male Female
9.7 (1.7) 9.7 (1.7)
0.90
Marital status Single Married
9.9 (1.3) 9.6 (1.8)
0.64
9.4 (1.4) 10.3 (2.1)
0.05
Smoking habits Non-smokers Smokers Activity Duration of education Occupation Age at onset of diabetes Duration of diabetes Extroversion Neuroticism Psychoticism
In conclusion, the present study has demonstrated that choice in favour of the multiple injection, basal-bolus insulin regimen over the more conventional twice daily, combined insulin regimen, was associated with a shorter duration of type 1 diabetes and a higher educational and professional status. Personality traits were not related to the choice of insulin regimen and similar levels of satisfaction with insulin therapy and quality of glycaemic control were evident with either insulin regimen.
Acknowledgements The authors wish to thank Mr S Ojo for collecting the data and the nursing staff of the Department of Diabetes of the Royal Infirmary of Edinburgh, for their co-operation with this study.
−0.134 −0.165 −0.078 0.014 −0.018 0.131 0.057 0.062
0.30 0.05 0.55 0.91 0.90 0.32 0.67 0.64
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