Hyperinsulinaemia Insulin Resistance and Cardiometabolic Risk Profile in Siblings of Type 2 Diabetics

Objective: To compare non-diabetic siblings of Type 2 diabetics for insulin resistance, hyperinsulinaemia, dyslipidemia and biometric indices with non diabetic volunteers with no family history of diabetes. Study Design: Cross sectional analytical study. Place and Duration of Study: A tertiary care teaching institution during Dec.2009 to July 2010. Methodology: Siblings of type 2 diabetics above the age of 25 years were matched as closely as possible for age, sex socioeconomic conditions with non diabetic volunteers with no family history of diabetes. Both groups were compared for fasting serum insulin, glucose, lipid levels and biometric indices using independent t-test. Insulin resistance was calculated by the Quicki (Quantitative insulin check index) method with cutoff at 0.34 on R.O.C analysis. Results: The 106 non diabetic siblings of Type 2 diabetes mellitus (Group 1) with a mean age of 40.8 ± 12.1 years p value 0.13 were compared to 106 non diabetic volunteers (Group 2) mean age 43.5 ± 14.2 years. Out of a total of 212 participants 20 (9.4%) subjects had hyperinsulinaemia (mean serum insulin15.69 ± 6.02 μU/L p 0.001) and insulin resistance (90% sensitivity CI 86 to 94, 98.96% specificity CI 97.7 to 100) and all belonged to group 1. A further comparison of the above variables was made within group 1 between 20 (9.4%) insulin resistant siblings and 86 (90.6%) non insulin resistant siblings. The insulin resistant siblings showed significant increase in HbA1c 7.02% ± 1.5 vs 6.2% ± 1.49 p = 0.008, BMI 30.4 ± 6.4 kg/m2 vs. 27.1 ± 4.7 kg / m2 p = 0.01and Serum insulin levels 15.92 ± 6.11 vs. 4.57 ± 2.38 p 0.001. Conclusion: The study suggests that siblings of diabetics are a special group who have hyperinsulinemia, insulin resistance and obesity and are at high risk for developing type 2 diabetes.