Abstract:
Insulin resistance and progressive beta-cell dysfunction have been identified as the two fundamental features in the pathogenesis of type 2 diabetes. The study was carried out to ascertain the aetiopathogenic and anthropometric factors in type 2 diabetes mellitus in Enugu State University Teaching Hospital, Enugu. One hundred and fifty (150) type 2 diabetes mellitus patients constituted the test subjects for the study while Fifty (50) of non- diabetic subjects free from hypertension served as control. Four milliliters of their fasting blood were collected, 2mls of which was dispensed into the fluoride oxalate bottles for glucose estimation and 2mls into plain tubes for c-peptide and insulin estimation. A questionnaire was administered to each of the subjects and these were used to extract demographic data. Insulin resistance and beta-cell function were estimated using homeostasis model assessment (HOMA) index. The result showed that the mean insulin level (8.06µlU/ml ± 0.56) and c-peptide level (1.33ng/ml ± 0.27) of the subjects were higher when compared to the controls (7.27µlU/ml ± 0.20) (p<0.001) and (1.10ng/ml ± 0.04) (p <0.01) respectively, though the mean serum insulin and c-peptide levels of both subjects and controls are within the normal range. However, HOMA-IR was significantly higher (3.14 ± 0.27) in diabetic subjects when compared with the controls(1.54 ± 0.04) while HOMA-B of the subjects was significantly lower (45.04 ± 3.78) compared to the controls(134 ± 8.86). Similarly, the mean FBS, BMI and diastolic blood pressure of the diabetic subjects were significantly higher when compared to their controls (p<0.001). Systolic blood pressure, WC and WHR were also significantly higher in diabetic subjects when compared with their controls.HOMA-IR strongly correlated positively with FBS and serum insulin (r =0.647, p<0.05; r =0.581, p<0.05) respectively. HOMA-B also showed very strong negative correlation with FBS (r=0.836, p <0.05) and strong negative correlation with serum insulin (-0.612, p<0.05). Both HOMA indexes have no correlation with systolic and diastolic pressure but correlated negatively with each other (r = -0.170, p<0.05). BMI and WC also showed positive correlation with HOMA-IR (r =0.240, p< 0.05; r = 0.315, P<0.05) but no correlation with HOMA-B (r =0.032, p>0.05; r = -0.104, p>0.05) respectively. However, there was negative correlation between HOMA-IR and age (r = -0.278, p<0.05) but no correlation between HOMA-B and age (r = 0.028, p>0.05). Duration of diabetes showed positive correlation with FBS (r = 0.322, p<0.05) and negative correlation with HOMA-B (r = -0.346, p<0.05). The higher HOMA-IR and lower HOMA-B with higher insulin and c-peptide levels suggest that type 2 diabetic patients have higher insulin resistance and lower beta-cell function though they secrete high insulin and c-peptide. Fasting blood sugar has been shown to be associated with insulin resistance, insulin secretion and duration of diabetes. Hence good glycemic control is necessary to improve insulin resistance and insulin secretion in patients with type 2 diabetes mellitus.
