PLASMA LEPTIN IS NOT ASSOCIATED WITH INSULIN-RESISTANCE AND PROINSULIN IN NONDIABETIC SOUTH ASIAN INDIANS

In an earlier study, we observed only a weak association between plasm a insulin (nonspecific assay) and leptin in South Asian Indians. This was in contrast to the observations in many other ethnic groups. With the availability of measurements of specific insulin (SI) and proinsul in (PI) in the same study group, we have reanalysed the data to look f or possible correlation of leptin with proinsulin and with insulin res istance calculated from the fasting values of specific insulin and glu cose using the HOMA model. Subjects with normoglycaemia (n = 117) and impaired glucose tolerance (n = 27, WHO criteria) were included in the analysis. Leptin values were higher in women. Multiple linear regress ion analysis showed that the variations in leptin concentrations in me n were associated with BMI, WHR, and 2 h SI values (R-2 = 56.2%) while fasting SI and proinsulin concentrations had no significant associati on. In women BMl and age showed a significant association with serum l eptin values (R-2 = 40.1%). Univariate and multivariate analyses using insulin resistance as the dependent variable showed that it had no as sociation with leptin in both genders. Leptin had no correlation with proinsulin also. This study confirmed that in Asian Indians the associ ation between plasma leptin and insulin concentrations is weak and tha t leptin has no influence on insulin resistance. Proinsulin and leptin are also not correlated in this population. Insulin resistance shows correlation with the beta-cell function both in men and women. (C) 199 8 John Wiley & Sons, Ltd.