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

Abstract

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 teach-ing 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 diabe-tic volunteers with no family history of diabetes. Both groups were compared for fasting serum insulin, glu-cose, 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 dia-betes mellitus (Group 1) with a mean age of 40.8 ± 12.1 years p value 0.13 were compared to 106 non dia-betic 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% sen-sitivity 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 sib-lings 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 dia-betics are a special group who have hyperinsulinemia, insulin resistance and obesity and are at high risk for developing type 2 diabetes.

Key words:  Hyperinsulinaemia, insulin resistance, BMI, siblings, metabolic syndrome.