A Study of insulin sensitivity in selected Nigerian subjects

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Fasanmade, O.A
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ABSTRACT: Insulin Sensitivity A study of insulin sensitivity was carried out on selected Nigerian subjects to measure insulin sensitivity in a group of diabetic subjects and non-diabetic controls. The relationship between insulin sensitivity and the clinical characteristics of the studied subjects were also to be determined. Patients with diabetes mellitus (DM) were studied as DM is the commonest endocrine disease known to be associated with insulin resistance (IR). The DM patients were recruited from the diabetes out-patients’ clinic of the Lagos University Teaching Hospital (LUTH). The control subjects were recruited from amongst the medical students and the workers of the LUTH. Both groups of the subjects were examined physically and their anthropometric indices measured and subsequently compared. The individuals in the study and control groups then had their insulin sensitivity estimated. This was done by calculating the glucose disappearance rates from the short insulin tolerance test (SITT). The SITT was performed on each subject in both groups and the results analysed. Different methods of calculating the Glucose disposal rate (GDR) during the tests were also analysed to identify the most accurate when compared with the analytical (the gold standard). Results of the clinical characteristics of the study and control group demonstrated differences mainly in the age, waist hip ratio and the fasting plasma glucose. For each of these parameters the diabetics had significantly higher values than the control subjects in both male and female subgroups. The body mass index (BMI), waist circumference and blood pressures were also higher in the diabetics than in the control group but these differences were not significantly higher. The GDR for the control subjects was 3.00mg/dL/min while for the diabetes it was 1.76mg/dL/min. Using values derived from the control subjects as reference points 31 and 141 of the male and female diabetics respectively were classified insulin sensitive. The observed difference in GDR values could not be attributed to differences in the anthropometric indices between the control and diabetic subject. There was strong correlation between the different methods of calculating the GDR from the SITT. The GDR was found to be higher in females than males. The GDR also was noted to decline with the age, BMI, WHR and waist circumference in both sexes. The correlations were however not significant except in the case of the females (with respect to age only). In conclusion the SITT has here been shown to be a practicable way of measuring insulin sensitivity. By the calculation of the GDR it has been found that IR is common in the diabetics studied. IR is also commoner in males and those with obesity, especially those with abdominal adiposity. It is however recommended that more studies need to be done in diabetics and non-diabetics to make far reaching conclusions on insulin sensitivity patterns in Nigerians
Insulin sensitivity, short insulin tolerance test, diabetes mellitus, Nigerians
Fasanmade OA. A Study of insulin sensitivity in selected Nigerian subjects. Part 2 Dissertation in part fulfilment of the Fellowship of the West African College of Physicians