Objective: The aim of the study was to assess the association of Insulin Resistance [IR] assessed by Homeostasis Assessment model (HOMA-IR) with cardiovascular risk factors in subjects with Normal Glucose Tolerance [NGT] in Asian Indians.
Methods: This cross-sectional study recruited subjects from the Chennai Urban Rural Epidemiology Study [CURES] an epidemiological study in a representative population of Chennai [formerly Madras], in South India. We included 1550 subjects with normal glucose tolerance, ie, fasting plasma glucose < 100 mg/dl [5.6 mmol/L] and 2 hour post load plasma glucose < 140 mg/dl [7.8 mmol/L]. IR was calculated using the homeostasis assessment model (HOMA-IR) using the formula: fasting insulin (1IU/mL) fasting glucose (mmol/L)/22.5. Metabolic syndrome [MS] was defined based on modified Adult Treatment Panel III (ATP III) guidelines.
Results: HOMA-IR was found to be significantly associated with systolic blood pressure (beta = 0.100, p < 0.001), diastolic pressure (beta = 0.094, p < 0.001), total cholesterol (beta = 0.068, p = 0.005), serum triglycerides (beta = 0.105, p < 0.001), LDL cholesterol (beta = 0.118, p < 0.005), and HDL cholesterol (beta = -0.060, p < 0.001) even after adjusting age, gender and BMI. Subjects with family history of type 2 diabetes had significantly higher HOMA-IR [p = 0.011] compared to those without family history. In relation to physical activity, subjects with heavy grade activity had significantly lower HOMA-IR values compared to the light grade activity [p < 0.001] Subjects with generalized obesity [p < 0.001] and abdominal obesity [p < 0.001] had significantly higher HOMA-IR which remained statistically significant even after adjusting for age and gender. There was a linear increase in the mean values of HOMA IR with increase in number of components of MS [p for trend < 0.001]
Conclusion: Among Asian Indians who are known to have high risk of premature coronary artery disease and diabetes, a significant association exists between insulin resistance with cardiovascular risk factors even among NGT subjects.