PROINSULIN AND INSULIN RESISTANCE IN CORONARY ARTERY DISEASE IN NON-DIABETIC SUBJECTS.

C. Snehalatha,,A.Ramachandran, K. Sathyavani,S.Sivasankari, Vijay Viswanathan. Diabetes Research Centre , Chennai.

Aim:The objective was to evaluate the association of plasma proinsulin and insulin resistance with coronary artery disease (CAD) in nondiabetic subjects.

Subject and Methods: In this study, 43 normoglycaemic men with angiographic evidence of CAD were compared with 55 normoglycaemic control men with no history or evidence of cardiac diseases.  Estimations of plasma glucose and lipid profiles were done.  Fasting plasma concentrations of specific insulin (SI) and proinsulin(PI) were estimated and mg  to specific insulin (PI/Six100) ratio were calculated.  Insulin resistance was calculated by the HOMA method, using the fasting glucose and specific insulin values.  Log transformation of skewed variables was done before group comparisons were made by the ‘t’ test.  Corrections for age and BMI were done in the PI and SI values before statistical comparisons were made.   Multiple logistic regression analysis was done to test the association of the variables with the prevalence of CAD. 

Results: Subjects in group 2 were older (P<0.001) and had higher BMI and waist to hip ratio.  The fasting plasma glucose values were similar in both groups.   Mean total cholesterol was higher and HDL – cholesterol level was lower in CAD.  Mean SI and PI values were higher in CAD  and the PI/SI ratios was also higher (P<0.001).  CAD group had a higher insulin resistance compared with the control group, which failed to reach statistical significance (P<0.054).

Conclusion:  The patients with CAD had significantly higher insulin, proinsulin and PI/SI ratio.  They also had an adverse lipoprotein profile in comparison with the control group.  Age, PI, serum cholesterol and low HDL Cholesterol showed independent associations with CAD.