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Diagnostic values of combined glucose and lactate values in cerebrospinal fluid and vitreous humour—our experiences
Forensic Science International 146S (2004) S19–S23 www.elsevier.com/locate/forsciint
Diagnostic values of combined glucose and lactate values in cerebrospinal fluid and vitreous humour—our experiences M.Z. Karlovsek Institute for Forensic Medicine, Medical Faculty, University of Ljubljana, Korytkova 2, 1000 Ljubljana, Slovenia Available online 20 October 2004
Abstract The final diagnosis of death in hypoglycaemic or diabetic coma should always be done as a synopsis of anamnestic response, morphology, biochemical (glucose, lactate, HBA1c, ketonic bodies, insulin, and C-peptide) and toxicological findings. High glucose levels in vitreous humour (more than 13 mmol/L, 234 mg/dL) or combined values of glucose and lactate in vitreous humour or in cerebrospinal fluid over threshold values of 23.7 mmol/L (427 mg/dL) and 23.4 mmol/L (422 mg/dL) respectively, can be an indicator of the pre-mortem hyperglycaemic state with fatal outcome. The determination of glycated haemoglobin, acetone and other ketone bodies improve the diagnostic values of the whole procedure. Diabetic ketoacidosis (blood aceton >0.3 g/L) is more often the cause of death of diabetic patients than the non-ketotic hyperosmolal state. Hypoglycaemia is deemed fatal if the combined values are lower than 5.5 mmol/L (100 mg/dL) and can not be excluded if they are lower than 8.9 mmol/L (160 mg/dL). Two cases of detected hypoglycaemia are described further. A psychiatric patient with diabetes (Hba1c 8.4%) committed suicide with an insulin overdose. The combined values of glucose and lactate in vitreous humour and in cerebrospinal fluid were 3.3 and 4.1 mmol/l, respectively. In another case a low combined glucose and lactate value (8.7 mmol/L) in vitreous humour indicated, besides the high concentration of glibenclamide (0.9 mg/L) in the blood of a driver with a poorly controlled diabetic condition (Hba1c = 10.6%), a state of decreasing blood glucose in the time before the accident causing the driver to feel unwell and behave inappropriately. # 2004 Published by Elsevier Ireland Ltd. Keywords: Post-mortem diagnosis; Hyperglycaemia; Hypoglycaemia; Combined glucose and lactate values; Cerebrospinal fluid; Vitreous humour
1. Introduction As morphological changes in diabetes mellitus are frequently not obvious or are insufficiently characteristic, a need arises for modest pathoanatomic findings to be complemented by additional thanatochemical or toxicological investigations, particularly in the case of fatal metabolic dysregulations, namely a fatal hypoglycaemic seizure and a fatal diabetic coma. Our interest is focused on parameters describing glycaemic states: glucose, lactate, glycated haemoglobin (HbA1c), E-mail address: [email protected].
ketonic compounds, insulin and other anti-diabetics, Cpeptide. Body fluid samples: blood, urine, vitreous humour and/or cerebrospinal fluid are taken during the section for the determination of these parameters.
2. Diabetic coma Glucose in the blood and other bodily fluids in the corpse simply disappeared in the early post-mortem period. The most important process contributing to this fact is glycolysis. Provided that there are a normal blood glucose level about
0379-0738/$ – see front matter # 2004 Published by Elsevier Ireland Ltd. doi:10.1016/j.forsciint.2004.09.006
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M.Z. Karlovsek / Forensic Science International 146S (2004) S19–S23
5.8 mmol/L (100 mg/dL), and the speed of the anaerobic catabolism by the erythrocytes approximately 0.72 mmol/L (13 mg/(dL h)), the whole blood-sugar will be metabolized to lactate within 8 h. Rapid chilling of the body inhibits glycolysis and thus results in higher glucose concentrations post-mortem [1]. In cases of pre-mortem and terminal hyperglycaemia, the relatively high concentrations of glucose in these body fluids generally continue to be encountered after death. According to Schleyer, the post-mortem liquor cerebrospinalis glucose over 200 mg/L (11.1 mmol/L) can be a sign of terminal hyperglycaemia [2]. Coe [3] observed vitreous humour glucose over 200 mg/dL only in cases with diabetes mellitus. After death, the concentration of lactate rises rapidly in extra-cellular fluids and could be up to 60 times higher than pre-mortem. Certain pathological states (acute infection, lacto-acidosis, malignomes etc.) and a prolonged agonal period lead to increases in lactate. On the other hand, low levels of lactate can accompany sudden death and a short agonal period [4,5]. In order to eliminate the negative effect of post-mortem glycolysis, Traub [6] introduced a new diagnostic criterion: the combined glucose and lactate level in the cerebrospinal fluid. The basis of this criterion was the assumption that lactic acid is the final product of post-mortem glycolysis (one molecule of glucose gives two molecules of lactic acid). This sum value should enable an evaluation of the terminal hyperor hypoglycaemic state for up to 105 h post-mortem. The sum value is time dependent and slowly increases after death. The idea of the sum value found an interest and many researchers [7–14] tried to find the diagnostic meaning of the combined glucose and lactate value in cerebrospinal fluid and/or in vitreous humour. According to their research the upper threshold values were decided upon, which predict decompensated diabetes mellitus with a fatal outcome with 95 or 99% probability. For liquor cerebrospinalis: 362 mg/dL [6], 400 mg/dL [7] 415 mg/dL [8], 422 mg/dL [9], and 500 mg/dL [10].
For corpus vitreum: 410 mg/dL [11], 427 mg/dL [9], 450 mg/dL [7], and 650 mg/dL [10] are calculated. The listed threshold levels are the result of measurements of glucose and lactate received with different analytical methods, the selections of different control groups and tolerance areas (95 and 99%). According to our study [9] the post-mortem glucose levels in vitreous humour are statistically significantly higher than in cerebrospinal fluid; the average lactate levels are significantly higher in cerebrospinal fluid than in vitreous humour in the group of diabetics and in control group. As a result there are no statistically significant differences between the combined glucose and lactate levels in vitreous humour and in cerebrospinal fluid in the control group and the calculated 99 % threshold values for the combined values which are 427 and 422 mg/dL for vitreous humour and cerebrospinal fluid, respectively. The correlation study led to the conclusion that HBA1c and combined value in vitreous humour provide the best information on the pre-mortal glycaemia. The addition of lactate increases the degree of correlation and raises the significance of the relationship between the glycaemic parameters (glucose, sum value) and glycated haemoglobin. Many laboratories still use units of glucose and lactate expressed in mg/dL or mg%. Conversion of threshold values expressed in conventional mg/dL units into SI mass units (mmol/L) is possible by dividing by 18. The combined glucose and lactate value in mmol/L is calculated as a sum of the concentration of glucose (mmol/L) plus concentration of lactose (mmol/L) divided by two. Expressions for the upper threshold values in vitreous humour are as given further. Glucose (mg/dL) + lactate (mg/dL) > 427 mg/dL. Glucose (mmol/L+ lactate (mmol/L) /2 > 23.7 mmol/L. The graphical representation of the calculated threshold value is also possible as a line in a lactate–glucose
Fig. 1. Lactate–glucose diagram for the group of diabetics, n = 41, with the line represented the upper threshold value in vitreous humour [9].
M.Z. Karlovsek / Forensic Science International 146S (2004) S19–S23
diagram with a segment of 47.9 mmol/L on ordinate and of 23.7 mmol/L on abscissa axe (for the vitreous humour) (Fig. 1). The points which lie in the right portion of the plane have crossed the threshold level and can indicate a dangerous pre-mortem state leading to death by diabetic coma. The contribution of lactate or glucose to the sum value can be seen separately as the ordinate value or the abscissa value. The vitreous humour glucose values in the diabetic group right to limit line (or above the 13 mmol/L regarding that the average lactate value in the diabetic group is 20.8 mmol/L) have a sizeable informational level and are an indication of pre-mortem hyperglycemia. The threshold value for HbA1c is 10%.
S21
tions confirmed low blood concentrations of the antipsychotic lozapine (0.05 mg/L), no ethanol in the blood, and an insulin concentration of 872 mE/L (reference fasting values for insulin in plasma are 2–25 mE/L). Biochemical analyses of biological material, taken 75 h post-mortem, gave very low glucose, lactate and combined values in cerebrospinal liquid and vitreous humour (Table 1). In this case where hetero-anamnestic, toxicological, pathomorphological and histological results suggest death due to hypoglycaemia, the combined values of glucose and lactate were under the threshold limit of 5.5 mmol/L (100 mg/L).
The supplementary determination of acetone and other ketone bodies improve the diagnostic values of the whole procedure. The high acetone values in body fluids (blood acetone >0.3 g/L, corpus vitreum acetone >0.4 g/L) observed during the routine gas-chromatographic ethanol and other volatile analyses are the warning sign of a fatal diabetic ketoacidosis [15].
5. Case 2 On 17 February, at 06.00, a 64-year-old man left home to go to the doctor. On the way, he stopped at a highway rest area. He then started driving in the opposite direction on the same one-way lane back home for no apparent reason. He crashed into a car and died at the scene of the accident. According to a relative, the deceased was a very conscientious person. A few months before, he was diagnosed with diabetes mellitus and put on an anti-diabetic therapy of 2.5 mg glibenclamide daily. However, the therapy was not successful. On his last visit to the doctor on 10 February, his fasting blood glucose concentration was 22.2 mmol/L (400 mg/dL). The traffic accident occurred on the way to a diabetologist. The deceased was expecting to be put on an insulin injection therapy, which apparently terrified him. The postmortem examination was conducted at 09.30 the next day. Several injuries were established as the cause of death, including contusions and extensive lacerations of the heart, lacerations of pericardium, lacerations of the aorta, severed left pulmonary artery, contusions and lacerations of the lungs, lacerated spleen and liver, lacerated diaphragma thoraco-abdominale, lacerated muscles and thoracic walls, lacerated pancreas, laceration of omentum majus, broken pelvis, backbone and thoracic bones, and breaks in all the long bones of the left upper and lower extremities. Arteriosclerotic changes were observed in major blood vessels (aortas, coronary arteries, brain arteries) as well as hypertrophy of the heart. The stomach was empty, whereas the duodenum and the small intestine contained some thick grey fluid.
3. Hypoglycaemia Indicators which support the theory that a person was hypoglycaemic at the time of death are the following. Low or indeterminate glucose concentrations in vitreous humour immediately after death. Extremely low glycated haemoglobin in treated diabetes patients as a consequence of periodically repeating hypoglycaemic states [16]. Low combined glucose and lactate values in cerebrospinal fluid and/or vitreous humour (<160 or 8.9 mmol/L [9] or <100 or <5.5 mmol/L [3]) even with signs of poor metabolically regulated diabetes mellitus (high HbA1c) [6,7]. Biochemical and toxicological findings indicating an overdose of insulin or anti-diabetics. 4. Case 1 A psychiatric patient committed suicide by insulin overdose. The patient was a metabolically regulated diabetic, a fact confirmed by value of glycated haemoglobin (HBA1c = 8.4%, good glucose control index). Toxicological examina-
Table 1 Biochemical parameters in the case of a hypoglycaemic state with fatal outcome: suicide of a diabetic patient with insulin overdose Biological fluid
Ketone bodies
Glucose
Lactate
Combined glucose and lactate values
HbA1c
Blood Urine Vitreous humour (mmol/L) Cerebrospinal fluid (mmol/L)
– Negative – –
Negative Negative 0.00 0.00
– – 6.1 8.9
– – 3.1 4.5
8.4% (good glucose control index)
S22
M.Z. Karlovsek / Forensic Science International 146S (2004) S19–S23
Table 2 Biochemical parameters in the hypoglycaemic state associated with the traffic accident Biological fluid
Ketone bodies
Glucose
Lactate
Combined glucose and lactate values
HbA1c
Blood Urine Vitreous humour (mmol/L)
– Negative –
Negative Negative 0.00
– – 17.4
– – 8.7
10.6% (poor glucose control index)
The cause of death was obviously polytrauma. However, we were interested in why the deceased stopped at the resting area and continued his journey in the wrong direction. At the time of post-mortem examination, which occurred 27 h after death, several biological samples were taken for histological analysis, including blood and urine samples for alcoholometric and toxicological analysis, and samples of blood, urine and the vitreous humour for biochemical analysis. Within the toxicological analysis, alcoholometry was performed and blood and urine were tested for medications. Ethanol was not present in the blood or urine. Glibenclamide in the blood was measured using gas chromatography [17]. The concentration in blood was 0.9 mg/L, which was higher than the usual therapeutic levels (0.17–0.36 mg/L) [18]. Biochemical analysis of the blood included a blood glucose assay with the ‘‘Dexstrostix’’ screening test and an assay of glucose and ketone bodies in the urine using the ‘‘Ketostix’’ screening test. Glucose and lactate in vitreous humour was measured with quantitative enzymatic methods (hexokinase and lactate dehydrogenase, respectively). HbA1c was measured with HPLC. The results are shown in Table 2. Glucose was not detected in the blood, urine or vitreous humour. Lactate was present in a medium to high post-mortem concentration, whereas the glycated haemoglobin level indicated a metabolically poorly regulated diabetes patient. The value of glycated haemoglobin (Hba1c = 10.6%) which reflects the integral concentration of glucose in blood during the last weeks before death indicates poor diabetic control. In a diabetes patient with such abnormally high HbA1c, terminal hyperglycaemia would be expected as well as measurable concentrations of glucose in the blood and vitreous humour at the time of the post-mortem examination. However, there are many arguments that indicated or confirm possible low blood glucose values in this case. Levels of glibenclamide (over therapeutic values). Fasting (empty stomach). Low combined value of glucose and lactate, which is somewhat higher than the fatal hypoglycaemia threshold of 5.5 mmol/L, but is still low enough (less than 8.9 mmol/L) to allow us to assume that the concentration was decreasing in the time before the accident, causing the driver to feel unwell and behave inappropriately.
The driver probably intentionally increased his dosage and missed a meal before going to the doctor. Due to the decreasing blood glucose levels he probably did not feel well nor was he able to think clearly, which was the reason he continued his journey on the wrong side of the road.
References [1] G. Kernbach, B. Brinkmann, Biochemical measurements of glucose metabolism in relation to cause of death and postmortem effects, Z. Rechtsmed. 96 (1986) 199–213. [2] F. Schleyer, Determination of the time of death in the early post-mortem interval, in: F. Lundquist (Ed.), Methods of Forensic Science, 2, Wiley, New York, 1963, pp. 253–293. [3] J.I. Coe, Postmortem chemistries on human vitreous humor, Am. J. Clin. Pathol. 51 (1969) 741–750. [4] V.J.M. DiMaio, W.Q. Sturner, J.I. Coe, Sudden unexpected deaths after the acute onset of diabetes mellitus, J. Forensic Sci. 22 (1977) 147–151. [5] JI. Coe, Postmortem chemistry update: emphasis on forensic application, Am. J. Forensic Med. Pathol. 14 (1993) 91–177. [6] F. Traub, Methode zur Erkennung von to¨ dlichen Zuckerstoffwechselstoerungen an der Leiche, Zbl. Allg. Path. 112 (1969) 390–399. [7] S. Ritz, H.J. Kaatsch, Postmortale Diagnostik von to¨ dlichen diabetischen Stoffwechelentgleisungen: welchen Stellenwert haben Liquor und Glasko¨ rperflu¨ ssigkeitssummenwerte sowie die HbA1-Wert, Pathologe 11 (1990) 158–165. [8] G. Kernbach, B. Brinkmann, Postmortale Pathochemie fu¨ r die Feststellung der Todesursache ‘‘Coma diabeticum’’, Pathologe 4 (1983) 235–240. [9] M. Zorec Karlovsek, Post-mortem diagnosis of diabetes mellitus and diabetic coma: a comparison of HbA1, glucose, lactate and combined glucose and lactate values in vitreous humour and in cerebrospinal fluid, in: B. Jacob, W. Bonte (Eds), Advances in Forensic Sciences: Forensic Criminalistic 2, vol. 4, Verlag Dr. Ko¨ stner, Berlin, 1995, pp. 38–48. [10] J. Kugler, M. Oemichen, Untersuchungen zum Glucosestoffwechsel an der Leiche, Beitr. Gerichtl. Med. 44 (1986) 185– 188. [11] H. Sippel, M. Mo¨ tto¨ nen, Combined glucose and lactate values in vitreous humour for post-mortem diagnosis of diabetes mellitus, Forensic Sci. Int. 19 (1982) 217–222. [12] E. Osuna, et al. Glucose and lactate in vitreous humor compared with the determination of fructosamine for the postmortem diagnosis of diabetes mellitus, Am. J. Forensic Med. Pathol. 22 (2001) 244–249. [13] A.E.A. De Letter, M.A. Piette, Can routinely combined analysis of glucose and lactate in vitreous humour be useful in
M.Z. Karlovsek / Forensic Science International 146S (2004) S19–S23 current forensic practice! Am. J. Forensic Med. Pathol. 19 (1998) 335–342. [14] C. Pe´ clet, P. Picotte, F. Jobin, The use of vitreous humour levels of glucose, lactic acid and blood levels of acetone to establish antemortem hyperglycemia in diabetics, Forensic Sci. Int. 65 (1994) 1–6. [15] J.E. Smialek, B. Levine, Diabetes and decomposition: a case of diabetic ketoacidosis with advanced postmortem change, Am. J. Forensic. Med. Pathol. 14 (1) (1998) 98–101.
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[16] E.A.M. Gale, S. Walford, R.B. Tatersall, Nocturnal hypoglycaemia and haemoglobin A1, Lancet 314 (1979) 1240–1241. [17] D. Castoldi, O. Tofanetti, Gas chromatographic determination of glibenclamide in plasma, Clin. Chem. Acta 93 (1979) 195– 198. [18] M. Berger, et al. Suizidversuch mit Glibenclamid: Verlauf der Blutspiegel von Glucose, Insulin, Glibenclamid und C-peptid, Dt. Med. Wschr. 102 (1977) 586–587.
Diagnostic values of combined glucose and lactate values in cerebrospinal fluid and vitreous humour—our experiences M.Z. Karlovsek Institute for Forensic Medicine, Medical Faculty, University of Ljubljana, Korytkova 2, 1000 Ljubljana, Slovenia Available online 20 October 2004
Abstract The final diagnosis of death in hypoglycaemic or diabetic coma should always be done as a synopsis of anamnestic response, morphology, biochemical (glucose, lactate, HBA1c, ketonic bodies, insulin, and C-peptide) and toxicological findings. High glucose levels in vitreous humour (more than 13 mmol/L, 234 mg/dL) or combined values of glucose and lactate in vitreous humour or in cerebrospinal fluid over threshold values of 23.7 mmol/L (427 mg/dL) and 23.4 mmol/L (422 mg/dL) respectively, can be an indicator of the pre-mortem hyperglycaemic state with fatal outcome. The determination of glycated haemoglobin, acetone and other ketone bodies improve the diagnostic values of the whole procedure. Diabetic ketoacidosis (blood aceton >0.3 g/L) is more often the cause of death of diabetic patients than the non-ketotic hyperosmolal state. Hypoglycaemia is deemed fatal if the combined values are lower than 5.5 mmol/L (100 mg/dL) and can not be excluded if they are lower than 8.9 mmol/L (160 mg/dL). Two cases of detected hypoglycaemia are described further. A psychiatric patient with diabetes (Hba1c 8.4%) committed suicide with an insulin overdose. The combined values of glucose and lactate in vitreous humour and in cerebrospinal fluid were 3.3 and 4.1 mmol/l, respectively. In another case a low combined glucose and lactate value (8.7 mmol/L) in vitreous humour indicated, besides the high concentration of glibenclamide (0.9 mg/L) in the blood of a driver with a poorly controlled diabetic condition (Hba1c = 10.6%), a state of decreasing blood glucose in the time before the accident causing the driver to feel unwell and behave inappropriately. # 2004 Published by Elsevier Ireland Ltd. Keywords: Post-mortem diagnosis; Hyperglycaemia; Hypoglycaemia; Combined glucose and lactate values; Cerebrospinal fluid; Vitreous humour
1. Introduction As morphological changes in diabetes mellitus are frequently not obvious or are insufficiently characteristic, a need arises for modest pathoanatomic findings to be complemented by additional thanatochemical or toxicological investigations, particularly in the case of fatal metabolic dysregulations, namely a fatal hypoglycaemic seizure and a fatal diabetic coma. Our interest is focused on parameters describing glycaemic states: glucose, lactate, glycated haemoglobin (HbA1c), E-mail address: [email protected].
ketonic compounds, insulin and other anti-diabetics, Cpeptide. Body fluid samples: blood, urine, vitreous humour and/or cerebrospinal fluid are taken during the section for the determination of these parameters.
2. Diabetic coma Glucose in the blood and other bodily fluids in the corpse simply disappeared in the early post-mortem period. The most important process contributing to this fact is glycolysis. Provided that there are a normal blood glucose level about
0379-0738/$ – see front matter # 2004 Published by Elsevier Ireland Ltd. doi:10.1016/j.forsciint.2004.09.006
S20
M.Z. Karlovsek / Forensic Science International 146S (2004) S19–S23
5.8 mmol/L (100 mg/dL), and the speed of the anaerobic catabolism by the erythrocytes approximately 0.72 mmol/L (13 mg/(dL h)), the whole blood-sugar will be metabolized to lactate within 8 h. Rapid chilling of the body inhibits glycolysis and thus results in higher glucose concentrations post-mortem [1]. In cases of pre-mortem and terminal hyperglycaemia, the relatively high concentrations of glucose in these body fluids generally continue to be encountered after death. According to Schleyer, the post-mortem liquor cerebrospinalis glucose over 200 mg/L (11.1 mmol/L) can be a sign of terminal hyperglycaemia [2]. Coe [3] observed vitreous humour glucose over 200 mg/dL only in cases with diabetes mellitus. After death, the concentration of lactate rises rapidly in extra-cellular fluids and could be up to 60 times higher than pre-mortem. Certain pathological states (acute infection, lacto-acidosis, malignomes etc.) and a prolonged agonal period lead to increases in lactate. On the other hand, low levels of lactate can accompany sudden death and a short agonal period [4,5]. In order to eliminate the negative effect of post-mortem glycolysis, Traub [6] introduced a new diagnostic criterion: the combined glucose and lactate level in the cerebrospinal fluid. The basis of this criterion was the assumption that lactic acid is the final product of post-mortem glycolysis (one molecule of glucose gives two molecules of lactic acid). This sum value should enable an evaluation of the terminal hyperor hypoglycaemic state for up to 105 h post-mortem. The sum value is time dependent and slowly increases after death. The idea of the sum value found an interest and many researchers [7–14] tried to find the diagnostic meaning of the combined glucose and lactate value in cerebrospinal fluid and/or in vitreous humour. According to their research the upper threshold values were decided upon, which predict decompensated diabetes mellitus with a fatal outcome with 95 or 99% probability. For liquor cerebrospinalis: 362 mg/dL [6], 400 mg/dL [7] 415 mg/dL [8], 422 mg/dL [9], and 500 mg/dL [10].
For corpus vitreum: 410 mg/dL [11], 427 mg/dL [9], 450 mg/dL [7], and 650 mg/dL [10] are calculated. The listed threshold levels are the result of measurements of glucose and lactate received with different analytical methods, the selections of different control groups and tolerance areas (95 and 99%). According to our study [9] the post-mortem glucose levels in vitreous humour are statistically significantly higher than in cerebrospinal fluid; the average lactate levels are significantly higher in cerebrospinal fluid than in vitreous humour in the group of diabetics and in control group. As a result there are no statistically significant differences between the combined glucose and lactate levels in vitreous humour and in cerebrospinal fluid in the control group and the calculated 99 % threshold values for the combined values which are 427 and 422 mg/dL for vitreous humour and cerebrospinal fluid, respectively. The correlation study led to the conclusion that HBA1c and combined value in vitreous humour provide the best information on the pre-mortal glycaemia. The addition of lactate increases the degree of correlation and raises the significance of the relationship between the glycaemic parameters (glucose, sum value) and glycated haemoglobin. Many laboratories still use units of glucose and lactate expressed in mg/dL or mg%. Conversion of threshold values expressed in conventional mg/dL units into SI mass units (mmol/L) is possible by dividing by 18. The combined glucose and lactate value in mmol/L is calculated as a sum of the concentration of glucose (mmol/L) plus concentration of lactose (mmol/L) divided by two. Expressions for the upper threshold values in vitreous humour are as given further. Glucose (mg/dL) + lactate (mg/dL) > 427 mg/dL. Glucose (mmol/L+ lactate (mmol/L) /2 > 23.7 mmol/L. The graphical representation of the calculated threshold value is also possible as a line in a lactate–glucose
Fig. 1. Lactate–glucose diagram for the group of diabetics, n = 41, with the line represented the upper threshold value in vitreous humour [9].
M.Z. Karlovsek / Forensic Science International 146S (2004) S19–S23
diagram with a segment of 47.9 mmol/L on ordinate and of 23.7 mmol/L on abscissa axe (for the vitreous humour) (Fig. 1). The points which lie in the right portion of the plane have crossed the threshold level and can indicate a dangerous pre-mortem state leading to death by diabetic coma. The contribution of lactate or glucose to the sum value can be seen separately as the ordinate value or the abscissa value. The vitreous humour glucose values in the diabetic group right to limit line (or above the 13 mmol/L regarding that the average lactate value in the diabetic group is 20.8 mmol/L) have a sizeable informational level and are an indication of pre-mortem hyperglycemia. The threshold value for HbA1c is 10%.
S21
tions confirmed low blood concentrations of the antipsychotic lozapine (0.05 mg/L), no ethanol in the blood, and an insulin concentration of 872 mE/L (reference fasting values for insulin in plasma are 2–25 mE/L). Biochemical analyses of biological material, taken 75 h post-mortem, gave very low glucose, lactate and combined values in cerebrospinal liquid and vitreous humour (Table 1). In this case where hetero-anamnestic, toxicological, pathomorphological and histological results suggest death due to hypoglycaemia, the combined values of glucose and lactate were under the threshold limit of 5.5 mmol/L (100 mg/L).
The supplementary determination of acetone and other ketone bodies improve the diagnostic values of the whole procedure. The high acetone values in body fluids (blood acetone >0.3 g/L, corpus vitreum acetone >0.4 g/L) observed during the routine gas-chromatographic ethanol and other volatile analyses are the warning sign of a fatal diabetic ketoacidosis [15].
5. Case 2 On 17 February, at 06.00, a 64-year-old man left home to go to the doctor. On the way, he stopped at a highway rest area. He then started driving in the opposite direction on the same one-way lane back home for no apparent reason. He crashed into a car and died at the scene of the accident. According to a relative, the deceased was a very conscientious person. A few months before, he was diagnosed with diabetes mellitus and put on an anti-diabetic therapy of 2.5 mg glibenclamide daily. However, the therapy was not successful. On his last visit to the doctor on 10 February, his fasting blood glucose concentration was 22.2 mmol/L (400 mg/dL). The traffic accident occurred on the way to a diabetologist. The deceased was expecting to be put on an insulin injection therapy, which apparently terrified him. The postmortem examination was conducted at 09.30 the next day. Several injuries were established as the cause of death, including contusions and extensive lacerations of the heart, lacerations of pericardium, lacerations of the aorta, severed left pulmonary artery, contusions and lacerations of the lungs, lacerated spleen and liver, lacerated diaphragma thoraco-abdominale, lacerated muscles and thoracic walls, lacerated pancreas, laceration of omentum majus, broken pelvis, backbone and thoracic bones, and breaks in all the long bones of the left upper and lower extremities. Arteriosclerotic changes were observed in major blood vessels (aortas, coronary arteries, brain arteries) as well as hypertrophy of the heart. The stomach was empty, whereas the duodenum and the small intestine contained some thick grey fluid.
3. Hypoglycaemia Indicators which support the theory that a person was hypoglycaemic at the time of death are the following. Low or indeterminate glucose concentrations in vitreous humour immediately after death. Extremely low glycated haemoglobin in treated diabetes patients as a consequence of periodically repeating hypoglycaemic states [16]. Low combined glucose and lactate values in cerebrospinal fluid and/or vitreous humour (<160 or 8.9 mmol/L [9] or <100 or <5.5 mmol/L [3]) even with signs of poor metabolically regulated diabetes mellitus (high HbA1c) [6,7]. Biochemical and toxicological findings indicating an overdose of insulin or anti-diabetics. 4. Case 1 A psychiatric patient committed suicide by insulin overdose. The patient was a metabolically regulated diabetic, a fact confirmed by value of glycated haemoglobin (HBA1c = 8.4%, good glucose control index). Toxicological examina-
Table 1 Biochemical parameters in the case of a hypoglycaemic state with fatal outcome: suicide of a diabetic patient with insulin overdose Biological fluid
Ketone bodies
Glucose
Lactate
Combined glucose and lactate values
HbA1c
Blood Urine Vitreous humour (mmol/L) Cerebrospinal fluid (mmol/L)
– Negative – –
Negative Negative 0.00 0.00
– – 6.1 8.9
– – 3.1 4.5
8.4% (good glucose control index)
S22
M.Z. Karlovsek / Forensic Science International 146S (2004) S19–S23
Table 2 Biochemical parameters in the hypoglycaemic state associated with the traffic accident Biological fluid
Ketone bodies
Glucose
Lactate
Combined glucose and lactate values
HbA1c
Blood Urine Vitreous humour (mmol/L)
– Negative –
Negative Negative 0.00
– – 17.4
– – 8.7
10.6% (poor glucose control index)
The cause of death was obviously polytrauma. However, we were interested in why the deceased stopped at the resting area and continued his journey in the wrong direction. At the time of post-mortem examination, which occurred 27 h after death, several biological samples were taken for histological analysis, including blood and urine samples for alcoholometric and toxicological analysis, and samples of blood, urine and the vitreous humour for biochemical analysis. Within the toxicological analysis, alcoholometry was performed and blood and urine were tested for medications. Ethanol was not present in the blood or urine. Glibenclamide in the blood was measured using gas chromatography [17]. The concentration in blood was 0.9 mg/L, which was higher than the usual therapeutic levels (0.17–0.36 mg/L) [18]. Biochemical analysis of the blood included a blood glucose assay with the ‘‘Dexstrostix’’ screening test and an assay of glucose and ketone bodies in the urine using the ‘‘Ketostix’’ screening test. Glucose and lactate in vitreous humour was measured with quantitative enzymatic methods (hexokinase and lactate dehydrogenase, respectively). HbA1c was measured with HPLC. The results are shown in Table 2. Glucose was not detected in the blood, urine or vitreous humour. Lactate was present in a medium to high post-mortem concentration, whereas the glycated haemoglobin level indicated a metabolically poorly regulated diabetes patient. The value of glycated haemoglobin (Hba1c = 10.6%) which reflects the integral concentration of glucose in blood during the last weeks before death indicates poor diabetic control. In a diabetes patient with such abnormally high HbA1c, terminal hyperglycaemia would be expected as well as measurable concentrations of glucose in the blood and vitreous humour at the time of the post-mortem examination. However, there are many arguments that indicated or confirm possible low blood glucose values in this case. Levels of glibenclamide (over therapeutic values). Fasting (empty stomach). Low combined value of glucose and lactate, which is somewhat higher than the fatal hypoglycaemia threshold of 5.5 mmol/L, but is still low enough (less than 8.9 mmol/L) to allow us to assume that the concentration was decreasing in the time before the accident, causing the driver to feel unwell and behave inappropriately.
The driver probably intentionally increased his dosage and missed a meal before going to the doctor. Due to the decreasing blood glucose levels he probably did not feel well nor was he able to think clearly, which was the reason he continued his journey on the wrong side of the road.
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