Low Socioeconomic Status and Increased Risk of Severe Hypoglycemia in Type 1 Diabetes: A Systematic Literature Review

socioeconomic status and severe hypoglycemia 233

Low Socioeconomic Status and Increased Risk of Severe Hypoglycemia in Type 1 Diabetes: A Systematic Literature Review Anna M. Sawka1,2 MD PhD, Pauline Boulos3 MD MSc, Ashnoor S.Talib4 MD, Amiram Gafni5,6 PhD, Lehana Thabane5,7 PhD, Alexandra Papaioannou3,8 MD MSc, Gillian Booth1,9 MD MSc, Hertzel C. Gerstein3,10,11 MD MSc Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto,Toronto, Ontario, Canada Division of Endocrinology and Metabolism, Department of Medicine, University Health Network,Toronto, Ontario, Canada 3 Department of Medicine, McMaster University, Hamilton, Ontario, Canada 4 Resident, Department of Family Medicine, McMaster University, Hamilton, Ontario, Canada 5 Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada 6 Centre for Health Economics and Policy Analysis, Hamilton, Ontario, Canada 7 Centre for Evaluation of Medicines and St. Joseph’s Healthcare, Hamilton, Ontario, Canada 8 Division of Geriatrics, Department of Medicine, Hamilton Health Sciences, Hamilton, Ontario, Canada 9 Division of Endocrinology and Metabolism, Department of Medicine, St. Michael’s Hospital,Toronto, Ontario, Canada 10 Division of Endocrinology and Metabolism, Hamilton Health Sciences and McMaster University, Hamilton, Ontario, Canada 11 McMaster University Population Health Institute Chair in Diabetes Research, Hamilton, Ontario, Canada 1 2

A B S T R A C T OBJECTIVE

We systematically reviewed the literature to determine whether low socioeconomic status is associated with severe hypoglycemia in individuals with type 1 diabetes in developed countries. METHODS

We searched 7 electronic databases and retrieved 620 citations and 30 full-text papers, which were all independently reviewed by 2 investigators. Consensus was reached between reviewers on inclusion of studies. Data were abstracted by 1 investigator and verified by another investigator. R E S U LT S

Nine observational studies were included in the review (6 pediatric, 3 adult). Five of the studies were from Europe, 3 from the United States and 1 from Australia. A statistically significant independent association of low socioeconomic status with severe hypoglycemia (after adjustment for other variables) was reported in 4 studies. Address for correspondence: Anna M. Sawka Toronto General Hospital 200 Elizabeth Street, EN 12-212 Toronto, Ontario M5G 2C4 Canada Telephone: (416) 340-3678 Fax: (416) 340-3314 E-mail: [email protected]

R É S U M É OBJECTIF

Nous avons fait une analyse documentaire méthodique pour déterminer si un faible statut socioéconomique était associé à l’hypoglycémie grave chez des personnes atteintes de diabète de type 1 dans les pays développés. MÉTHODES

Nous avons fait des recherches dans sept bases de données électroniques et repéré 620 citations et 30 comptes rendus intégraux, lesquels ont tous été évalués indépendamment par deux examinateurs qui se sont entendus sur le choix des textes à retenir. Les données ont été extraites par un des examinateurs et vérifiées par l’autre. R É S U LTAT S

Neuf études par observation ont servi à réaliser l’évaluation (six menées chez des enfants et trois menées chez des adultes). Cinq des études avaient été menées en Europe, trois aux ÉtatsUnis et une en Australie. Quatre études ont signalé un lien indépendant statistiquement significatif entre un faible statut socioéconomique et l’hypoglycémie grave (après ajustement pour d’autres variables). CONCLUSIONS

Un faible statut socioéconomique pourrait être associé à une hausse de l’incidence de l’hypoglycémie grave en présence de diabète de type 1, mais le lien n’est pas systématique dans la documentation actuelle. M OT S C L É S

diabète, hypoglycémie, statut socioéconomique CANADIAN JOURNAL OF DIABETES. 2007;31(3):233-241.

CANADIAN JOURNAL OF DIABETES

234 CONCLUSIONS

Low socioeconomic status may be associated with an increased incidence of severe hypoglycemia in type 1 diabetes; however, this relationship has been inconsistently observed in the existing literature. K E Y WO R D S

Diabetes, hypoglycemia, socioeconomic status INTRODUCTION Hypoglycemia is an important limiting factor in the treatment of type 1 diabetes mellitus (1). Severe hypoglycemia is defined by the presence of autonomic and neuroglycopenic symptoms and an inability to self-treat with carbohydrate (2,3); it is responsible for approximately 2 to 4% of deaths of people with type 1 diabetes (4). In children with type 1 diabetes, severe hypoglycemia accounts for 8% of deaths (5). Hypoglycemia may also result in convulsions (6), injury (to self or others) (6), motor vehicle accidents (6), negative emotional and social consequences (7) and childhood cognitive or learning problems (8). In observational studies of type 1 diabetes patients, the incidence of severe hypoglycemia per person-year of follow-up is 0.1 to 2.8 in adults (6,9,10) and 0.03 to 3.6 in children (11-16). There are multiple clinical risk factors for severe hypoglycemia in type 1 diabetes, including hypoglycemic unawareness (10), a previous history of severe hypoglycemia (including associated seizure or injury) (6,17), duration of diabetes (or insulin therapy) (6,17), adolescence (18), undetectable C-peptide (18), tighter glycemic control (lower glycosylated hemoglobin [A1C]) (11,12,15,17), intensive insulin therapy (17-19), autonomic failure (20), younger age (in children) (12,15) and higher insulin dose (in children) (11,21). The potential influence of socioeconomic factors on the incidence of severe hypoglycemia in type 1 diabetes is not well understood. There has been recent interest in the relationship between socioeconomic status and health; individuals of higher socioeconomic status generally have better health and lower mortality rates than those who are less advantaged (22-24). But what defines socioeconomic status? Socioeconomic status has been traditionally defined by the domains of education, income and occupation (25). Additional measures may include personal wealth, material deprivation (such as lack of a vehicle or lack of home ownership) or perceived social status (26). Socioeconomic status can be measured at an individual or a group/aggregate level (for a community or neighbourhood) (22); neighbourhood-level socioeconomic status is independently predictive of health outcomes after adjustment for individual status (22). In the field of diabetes care, individuals of low socioeconomic status have been found to attend diabetes clinics (27), undergo routine blood tests (27) and self-monitor their blood

glucose (BG) (28,29) less frequently than individuals of higher socioeconomic status. Furthermore, individuals with type 1 diabetes who are of low socioeconomic status have been found to be less accepting of preventative and health maintenance behaviour compared to those from higher social strata (30).As well, individuals with diabetes who are of low socioeconomic status may also develop hypoglycemia in response to inadequate intake of food (31). Such factors may predispose these individuals to hypoglycemia, including severe lifethreatening events.The objective of this study was to systematically review the type 1 diabetes literature to determine whether low socioeconomic status is associated with an increased incidence of severe hypoglycemia. Knowledge of such an association may inform clinical practice and health policy in diabetes care delivery. METHODS Search strategy for relevant studies and data abstraction An electronic search was originally conducted by 1 investigator using the following databases (no language restrictions): Ovid Medline (1966 to March week 3, 2006), Ovid Medline in process (March 27, 2006), EMBASE (1980 to week 12, 2006), the Cochrane Database of Systematic Reviews (March 2006), ACP Journal Club (1991 to March 2006), the Database of Abstracts of Reviews of Effects (March 2006) and the Cochrane Central Register of Controlled Trials (March 2006). The search was updated on November 24, 2006, using the same databases and search strategy. The search terms in the electronic search included the MeSH heading hypoglycemia or root of text word hypoglyc or root of text word neuroglycopen; MeSH headings hierarchy (social), social change, social class, social conditions, social environment, social problems, social welfare, socioeconomic factors,career mobility,poverty,cost of illness,social welfare,medically uninsured,income or the text words social class,socioeconomic, socio-demographic, income or medically underinsured; and MeSH headings for diabetes mellitus or the root of text word diabet. All abstracts and citations retrieved by the electronic search were independently reviewed by 2 investigators. Any citation considered potentially relevant by either investigator was then reviewed by both investigators in full-text form. Consensus was reached between the 2 reviewers for inclusion of studies in the review. Data were abstracted by 1 investigator and tabulated.The tabulated data were then verified by a second investigator, with disagreements settled by consensus.

socioeconomic status and severe hypoglycemia 235

Inclusion and exclusion criteria We searched for cohort, cross-sectional and case-control studies of adults or children with type 1 diabetes in which the relationship between socioeconomic status and incidence of severe hypoglycemia was examined. The definition of severe hypoglycemia was based on either a definition provided in primary studies or on documented hypoglycemic episodes (plasma glucose below 4 mmol/L or 72 mg/dL) complicated by seizure, unconsciousness, unawareness, death, hospitalization or the need for parenteral glucose or glucagon. Measures of socioeconomic status included individual or neighbourhood level, education, income, occupation, wealth, material deprivation, social class (or perceived social status), medical insurance status, receipt of social assistance or a combination of any of these attributes. In the case of pediatric studies, measures of parental socioeconomic status were sought. We did not exclude based on the quality of the measure of socioeconomic status used, but we did exclude studies focusing on patients with end stage renal disease, diabetes in pregnancy, transplant-associated diabetes or secondary diabetes (for example, due to pancreatitis or medications).We also excluded studies from developing or undeveloped countries as defined by the 2004 World Bank classification (32). RESULTS Studies included in the review There were 620 unique references retrieved by the electronic search. Five hundred and ninety references were excluded

because they were not relevant to the study; 30 potentially relevant references were reviewed in full-text form (Figure 1). Nine papers meeting all of the inclusion criteria and none of the exclusion criteria were included in the final review (9,3340). Six of the 9 included studies focused on children or adolescents (33-38), and 3 of the studies were restricted to adults (age ≥18 years) (9,39,40) (Table 1). Five of the studies were conducted in Europe (the United Kingdom [including Scotland], France, Germany, Denmark) (9,34,38-40), 3 of the studies were performed in the United States (33,36,37) and 1 was performed in Australia (35). Four of the pediatric studies (33-35,37) and 2 of the adult studies (9,39) were examinations of cohorts, whereas 2 pediatric studies (36,38) and 1 adult study were purely cross-sectional (40). Demographic characteristics for participants in each study are shown in Table 1. The mean follow-up period in cohort studies was 1 year or longer, and losses to follow-up ranged from 0.5% to 15% in those studies reporting losses (9,33-35,37,39). Definitions of severe hypoglycemia and socioeconomic status Severe hypoglycemia was variably defined by low BG leading to loss of consciousness, seizure, emergency medical care, hospitalization or use of parenteral treatment (Table 2). Independent confirmation of severe hypoglycemia by medical personnel was performed in only 2 of the studies (9,34). Measures of socioeconomic status used in the primary studies are described in Table 3. Socioeconomic status was not

Figure 1. Process of exclusion of studies in the systematic review 620 unique references obtained from electronic searches

30 potentially relevant references reviewed in full-text form by 2 reviewers

9 studies included in review

590 references excluded since not relevant to this study

21 references excluded: 18: either severe hypoglycemia was not an outcome, socioeconomic status was not measured or the relationship between these variables was not examined (2 of these studies focused on type 2 diabetes patients) 1: review/commentary on hypoglycemia in general 1: hospitalizations for severe hypoglycemia grouped with those for severe hyperglycemia; separate event rates for severe hypoglycemia could not be extracted 1: study from developing country

CANADIAN JOURNAL OF DIABETES. 2007;31(3):233-241.

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236 Table 1. Characteristics of included studies Study

Year

Number Country of of study patients

Source of study population

Age of Duration of participants, diabetes, y y

Loss to follow-up for cohort studies (duration of follow-up)

≥ 50% of study population is <18 years of age) Studies of predominantly children or adolescents (≥ Allen (33)

2001

415

US

Regional registry of incident cases

<15 in 60.7%*

4–6.5*

Baumer (34)

1998

801

UK

Regional audit

<10, 27% 10–15.9, 51% ≥16, 21%*

<5, 55% 5–9.9, 31% ≥10, 14%*

Bulsara (35)†

2004

1335

Australia

Diabetes clinic

9.5 (mean)

Not stated*

0.5% (4.7 y, mean)

Overstreet (36)

1997

58

US

2 university clinics

11.6–12.6*

2.8–4.5*

NA§

Rewers (37)

2002

1243

US

Diabetes clinic

Rosilio (38)

1998

2579

France

Recruitment in clinics caring for children with diabetes

12.3 (mean)

5 (mean)

NA§

Leese (9)

2003

977 type 1 diabetes

Scotland

Regional registry and hospital admission data

33.1 (mean)

17 (mean)

Unclear (12 m)

Muhlhauser (39)

1998

684

Germany

Random sample of family practice patients with type 1 diabetes

36 (mean)

18 (mean)

PedersenBjergaard (40)

2004

1076

Denmark, UK

Hospital or university clinics

40 (mean)

21 (mean)

13 (median)‡

3.3 (median)‡

Unclear (4–6.5 y) 15% (12 m)

13.8% (3.5 y, mean)

Studies of adults

2% (19 m, mean) NA||

Mean not published for entire study population combined. The type of diabetes was not formally specified, but given the young age of participants, it is assumed that most of the participants had type 1 diabetes mellitus. ‡ Median age and duration of diabetes at the half-point of the follow-up period. § Cross-sectional study. || Response rate: 1076/1183 subjects. *

†

NA = not applicable

UK = United Kingdom

independently confirmed in most of the studies (9,33-36,3840), although medical insurance status may have been verified for billing purposes in an American clinic-based study (37). Group-based measures of material deprivation according to area of residence (including factors such as home ownership, access to a car, unemployment rate and overcrowding) were used in 3 studies (9,34,35). Individual-based measures of socioeconomic status were employed by the remaining studies, including measures of medical insurance status (2 American studies) (33,37), parental or personal occupational prestige (33,36,38,39) or highest level of education (40).

US = United States

Incidence of severe hypoglycemia and relationship with socioeconomic status The incidence of severe hypoglycemia was 13.6 to 45 events per 100 person-years in children (35,37,38) and 11.5 to 130 events per 100 person-years in adults (9,39,40) (Table 4).The highest incidence rates of severe hypoglycemia in children (38) and adults (40) were, notably, participant-reported. One or more measures of low socioeconomic status were significantly associated with an increased incidence of severe hypoglycemia in at least 1 univariate or multivariate analysis in 8 of the 9 included studies (9,33-37,39,40) (Table 5); the

socioeconomic status and severe hypoglycemia 237 Table 2. Definitions of severe hypoglycemia Study

Definition of severe hypoglycemia

Studies of predominantly children or adolescents (≥50% of study population is <18 years of age) Allen (33)

Loss of consciousness during an insulin reaction

Baumer (34)

Hospital admission for hypoglycemia

Bulsara (35)

A hypoglycemic event leading to loss of consciousness or seizure

Overstreet (36)

Episodes of hypoglycemia unconsciousness

Rewers (37)

A hypoglycemic reaction leading to loss of consciousness or seizure, or resulting in an emergency department visit or hospital admission

Rosilio (38)

Severe hypoglycemia defined by at least 1 of the 3 following criteria: loss of consciousness, seizures, glucagon injection

Studies of adults Leese (9)

Blood glucose <63 mg/dL (<3.5 mmol/L) associated with the need for treatment with glucagon or intravenous dextrose to effect recovery, or paramedic confirmation of hypoglycemia with rapid recovery from treatment. Episodes of hypoglycemia were identified by use of medical services

Muhlhauser (39)

Self-reported history of hypoglycemic reaction treated with glucagon or glucose injection by a relative or physician

PedersenBjergaard (40)

Self-reported history of severe hypoglycemia defined as episodes where assistance from others was needed to restore blood glucose and were reported for the preceding 1- to 2- year periods

Table 3. Measurement of socioeconomic status Study

Measurement of socioeconomic status (individual or aggregate)

Studies of predominantly children or adolescents (≥50% of study population is <18 years of age) Allen (33)

Individual: Socioeconomic Index (occupation-based scale), mother’s years of education, health insurance (Medicaid, private or other)

Baumer (34)

Aggregate:Townsend Deprivation Index for postal code of residence of each child (incorporates percentage of households with access to a car, percentage of households not in owner-occupied accommodation, percentage of households overcrowded, percentage unemployment)

Bulsara (35)

Aggregate: Index of Relative Socioeconomic Disadvantage for regions of Australia (Australian Bureau of Statistics) (incorporates prevalence of low income earners, educational attainment, unemployment rate, rented dwellings, people lacking fluency in English)

Overstreet (36)

Individual: Hollingshead Index of Social Position (based on parental occupational ranking and education)

Rewers (37)

Individual: medical “underinsurance” defined as a lack of private insurance, receiving Medicaid, participation in the Colorado Resident Discount Program, having Child Health Plan Plus

Rosilio (38)

Individual: monthly income of parents; parental socio-professional status graded according to the scale of the Institut National de la Statistique et des Études Économiques

Studies of adults Leese (9)

Aggregate: Carstairs-Morris Index of social deprivation (UK data used to calculate a single score for each postal code area, incorporating information on unemployment, overcrowding, car ownership, social class)

Muhlhauser (39)

Individual: social class score based on instruments used in previous health surveys in Germany (includes highest educational level, household income, present/last employment level)

PedersenBjergaard (40)

Individual: educational level (high school compared to primary school and university compared to primary school, respectively) CANADIAN JOURNAL OF DIABETES. 2007;31(3):233-241.

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238 Table 4. Incidence of severe hypoglycemic reactions in included studies Study

Incidence of severe hypoglycemic reactions

Comments

≥ 50% of study population is <18 years of age) Studies of predominantly children or adolescents (≥ Overall incidence of events not clearly stated

1987 severe hypoglycemic events in 415 patients over the course of the study

Baumer (34)

Overall incidence of events not clearly stated

4.1% of children seen over the 12-month period were admitted with hypoglycemia

Bulsara (35)

13.6 events per 100 person-years

944 severe hypoglycemic events during 6928 person-years of follow-up

Overstreet (36)

Incidence not available (cohort study)

Average number of episodes of hypoglycemia-related loss of consciousness reported over course of entire disease by patients was approximately 0.1 to 0.5, grouped by race and socioeconomic status

Rewers (37)

19 events per 100 person-years

768 events per 3994 person-years

Rosilio (38)

45 events per 100 person-years (self-recalled)

593 episodes over the preceding 6 months in 338/2579 children

Allen (33)

Studies of adults Leese (9)

11.5 episodes per 100 person-years (type 1 diabetes)

–

Muhlhauser (39) 20 episodes per 100 person-years

208 events in 100/669 patients

PedersenBjergaard (40)

Total number of events not provided, but number of subjects was 1076

130 episodes per 100 person-years (selfrecalled)

only study in which no significant evidence of any association was observed was a large, pediatric, clinic-based study from France (38). Moreover, a statistically significant independent association of low socioeconomic status with severe hypoglycemia (after adjustment for other variables) was reported in 3 pediatric studies (34,35,37) and 1 adult study (39). DISCUSSION In summary, low socioeconomic status was found to be associated with an increased incidence of severe hypoglycemia (both variably defined) in 8 of 9 studies examined in this review (9,33-37,39,40). However, independent associations of low socioeconomic status and severe hypoglycemia were reported in only 4 of the included studies (34,35,37,39). Limitations of most of the included studies included lack of independent confirmation of severe hypoglycemic events by healthcare professionals (exceptions are studies by Leese et al [9] and Baumer et al [34]).This review is also limited by variability in the included studies’ study population (adults and children from various countries), methodology (crosssectional or cohort designs), definition of socioeconomic status and healthcare delivery system. Why should socioeconomic status influence hypoglycemic outcomes in diabetes? Pathways by which socioeconomic status

could generally influence health include biological determinants, access to quality healthcare, environmental exposure, and behaviour or lifestyle (25). It is possible that lack of access to food (31), insufficient access to high-quality diabetes care, lack of resources for sufficient BG monitoring and negative lifestyle choices could explain an association between low socioeconomic status and severe hypoglycemia in type 1 diabetes. There is known to be a relationship between low socioeconomic status and less frequent attendance at diabetes clinics (27) and lower rates of BG self-monitoring (28,29). Also, individuals of low socioeconomic status also have been reported to have fewer psychosocial resources, chronic psychological stress, impaired coping and increased hopelessness (41) — factors that contribute to negative lifestyle choices. The association between low socioeconomic status and severe hypoglycemia is unlikely to be a simple reflection of increased incidence or prevalence of type 1 diabetes in individuals of low socioeconomic status; the relationship between low socioeconomic status and epidemiology of type 1 diabetes has been found to be positive (42,43), inverse (44-47) or not statistically significant (48). Brown and colleagues previously described a conceptual framework explaining the relationship between socioeconomic position and health outcomes in diabetes (27).Within this framework, socioeconomic status across the life course is

socioeconomic status and severe hypoglycemia 239 Table 5. Strength of association of socioeconomic status with incidence of severe hypoglycemic episodes Study

Patients Type of analysis in final (variables in model) model (N)

Strength of association of socioeconomic status with severe hypoglycemia, OR or RR or HR (95% CI) (p value)

≥ 50% of study population is <18 years of age) Studies of predominantly children or adolescents (≥ Allen (33)

415

Univariate generalized estimating equations

Baumer (34)

635

Multivariable; type of statistical test unclear (model 6-point increase in deprivation on Townsend Deprivation adjusted for age, dose of insulin, medical consultIndex: OR=2.18 (1.09, 4.38) (p=0.031) ant group)

Bulsara (35)

Final N unclear, Multivariable regression (model adjusted for age, original sex, A1C, number of injections, daily insulin dose N=1335 in U/kg)

Overstreet (36)

Rewers (37)

Rosilio (38)

OR • Mother’s education, y: 1.0 (0.9, 1.2) • Occupational code, quartile 2 vs. 1: 0.8 (0.4, 1.6) • Occupational code, quartile 3 vs. 1: 0.7 (0.4, 1.5) • Occupational code, quartile 4 vs. 1: 0.9 (0.5, 1.7) • Health insurance, Medicaid vs. other: 10.5 (1.2, 95.7) • Health insurance, private vs. other: 2.4 (0.3, 17.2)

58

Univariate ANOVA

RR with Index of Relative Socioeconomic Disadvantage: • Lowest (best) vs. highest (worst): 0.7 (0.5, 0.9) (p=0.028) • Middle vs. highest (worst): 0.6 (0.4, 0.9) (p=0.004) Low socioeconomic status (grades IV to V Hollingshead Index of Social Position) had significantly more hypoglycemic episodes (with unconsciousness) than middle to upper socioeconomic groups (grades I to III), F=4.12 (degrees of freedom 1,53) (p<0.05)

Final N unclear, original N=1243

Poisson multivariable backward stepwise regresUnderinsurance RR: sion, analysis stratified by gender and age (age <13 • Age <13 y: 1.33 (1.08, 1.65) (p<0.008) and age ≥13 y) (model for age <13 y adjusted for • Age ≥13 y: 1.42 (1.11, 1.81) (p<0.005) diabetes duration; model for age ≥13 y adjusted for diabetes duration, A1C, presence of psychiatric disorders)

Final N unclear, original N=2579

Multivariable stepwise logistic regression (initial model included the following “qualitative” variables: sex, family support score, father’s employment or family income if father unemployed, maternal language, presence of a sibling with diabetes, study centre characteristics)

“No qualitative variable could explain the occurrence of hypoglycemic episodes” (i.e. father’s employment or income if father not employed was not significantly associated with severe hypoglycemia; exact estimates of association not provided in paper)

Studies of adults Leese (9)

Final N unclear Univariate Cochran-Mantel-Haenszel test for type 1 diabetes

Increased deprivation on Carstairs-Morris score was associated with increased incidence of severe hypoglycemia (p<0.001 for type 1 diabetes)

Muhlhauser (39)

627

Multivariable Cox proportional hazards model (with backwards selection) (final model adjusted for history of severe hypoglycemia in the previous 12 months, blood glucose target <7.8 mmol/L, C-peptide negativity, any history of severe hypoglycemia necessitating assistance)

PedersenBjergaard (40)

1076

• Univariate and multivariate analyses examining • In univariate analysis, high school education compared associations with rate of severe hypoglycemia: to primary school education was found to be signifi“frailty model for recurrent events (an extension cantly associated with rate of severe hypoglycemia: of the log-linear Poisson model including a gammaRR=0.57 (0.38, 0.85) (p=0.0057) distributed variation between patients)” (40) • In univariate analysis, university education compared • The multivariable model predicting rate of to primary school education was not found to be sigself-reported hypoglycemia included state of nificantly associated with rate of severe hypoglycemia: awareness, age, duration of diabetes, A1C, antiRR=0.89 (0.65, 1.22) (p=0.46) hypertensive therapy, weight adjusted for insulin • In multivariable analysis, education level was not found dose, peripheral neuropathy, level of education, to be significantly associated with rate of severe hypomarital state, smoking glycemia

A1C = glycosylated hemoglobin ANOVA = analysis of variance

HR = hazard ratio OR = odds ratio

Social status (using a German multi-attribute score, where 0=lowest social level and 24=highest social level): time to first severe hypoglycemic episode for 5 unit increase in social status, HR=0.78 (0.63, 0.96) (p=0.0162)

RR = relative risk SES = socioeconomic status CANADIAN JOURNAL OF DIABETES. 2007;31(3):233-241.

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240

thought to encompass individual socioeconomic status, social relationships, community-level characteristics and gradients of socioeconomic position at the individual and community levels. Socioeconomic position may influence health outcomes through individual health behaviours, access to care and process of care (the latter including technical and interpersonal care provided to patients within the healthcare setting). However, the extent to which the components of this framework may influence the risk of severe hypoglycemia in type 1 diabetes is unknown. CONCLUSIONS Low socioeconomic status may be associated with an increased risk of severe hypoglycemia in children and adults with type 1 diabetes, although this relationship has been inconsistently observed in the literature. Furthermore, if such a relationship exists, it is unclear whether it is independent of other clinical, lifestyle or social variables. Further study is needed to confirm and better understand the possible connections between socioeconomic status and hypoglycemic outcomes in diabetes.As well, potential disparities in diabetes care delivery affecting individuals of low socioeconomic status should be explored by health policy makers. Given the findings of this review, it may be important for clinicians to consider socioeconomic factors in the evaluation of patients with type 1 diabetes presenting with severe hypoglycemia. In the meantime, specific strategies that could be considered by healthcare providers to try to decrease the risk of severe hypoglycemia in individuals with type 1 diabetes and low socioeconomic status could include a) ensuring adequate patient education on hypoglycemia and its treatment; b) specifically asking about frequency and severity of hypoglycemia at patient care visits; c) provision of glucose tablets and glucagon injection kits; d) dietary education on meal planning, as well as education about the potential impact of variables such as exercise or alcohol on the risk of hypoglycemia; and e) if needed, referral to social services professionals for information on social funding sources or provision of information on local food banks. For individuals not willing or able to obtain counselling on diabetes management through a healthcare provider or diabetes education program, information resources on hypoglycemia and its treatment could be provided through local pharmacies, for distribution when insulin prescriptions are filled. ACKNOWLEDGEMENTS The authors thank Drs. Jan Sargeant and Lonnie Zwaigenbaum for their methodological advice. The authors also thank Shahryar Murshed for assistance with data retrieval and checking. AMS and GB are Canadian Institutes of Health Research New Investigators. AUTHOR DISCLOSURES No dualities of interest declared.

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