Relation of direct and surrogate measures of insulin resistance to cardiovascular risk factors in nondiabetic finnish offspring of type 2 diabetic individuals.

Description

The purpose of this study was to compare surrogate indices of insulin resistance with the gold standard (the euglycemic-hyperinsulinemic clamp), as well as their relationship with cardiovascular risk factors. The study sample included 272 nondiabetic Finnish offspring of type 2 diabetic individuals (age 24-50 years; 55% female). Results showed that various indices derived from either fasting values or oral glucose tolerance test (OGTT) sampling times were valid measures of insulin resistance across sex, glucose tolerance, and body mass index categories. Moreover, Matsuda index, simple index assessing insulin sensitivity using OGTT measurements (ISOGTT), and Avignon’s insulin sensitivity index (Avignon’s SiM) were the strongest correlates of directly measured insulin sensitivity by euglycemic-hyperinsulinemic clamp (MLBM/I). Indices based on fasting measurements were mostly similar to MLBM/I in their relationships with metabolic variables. The correlation of McAuley index with lipoproteins and the Framingham risk score was particularly strong. Indices based on OGTT sampling times were also largely similar to MLBM/I. Still, Matsuda index had more robust relationships with blood pressure and fasting insulin and glucose levels. Indices with a measure of adiposity in their formula, such as Avignon’s SiM and Stumvoll indices had stronger correlations with adiposity, blood pressure, fasting insulin concentration, fibrinogen and Framingham risk score. Thus, surrogate indices are valid measures of insulin resistance. In their editorial comment, Buchanan TA et al. raised the question whether the conclusions of this study were valid since they were based only on correlations. They discussed the fact that correlations did not permit a valid assessment of quantitative relationship between two measures of insulin resistance. They also added that surrogate measures did not perform very well in genetic or longitudinal studies.