Insulin sensitivity and clustering of coronary heart disease risk factors in young adults. The Northern Ireland Young Hearts Study

Background. Coronary heart disease (CHD) is usually associated with “clustering” of risk factors. Insulin resistance may cause deleterious changes in several CHD risk factors and is of potential interest in the aetiology of clustered risk. We analyzed how glucose and insulin variables were associated with clustered risk. Methods. Participants were 489 young adults from Northern Ireland. Data were collected between October 1997 and October 1999. Nine risk factors were included in the clustered risk variable. Being “at risk” was defined as being in the upper quartile of risk for a particular risk factor. Subjects with clustered risk were defined as those displaying four or more risk factors. Blood glucose and insulin were measured in the fasting state and 2 h after ingestion of a 75 g glucose load. Results. Fasting insulin and the homeostasis model assessment insulin resistance score (HOMA) were strong, graded predictors of clustered risk. The odds ratio (OR) for having clustered risk was 10.8 (95% CI: 3.6–32.4) for the upper quartile of fasting insulin compared to the lowest quartile, and the corresponding OR for HOMA was 23.2 (95% CI: 5.3–101.6). Conclusion. HOMA score predicts clustering of CHD risk factors. Fasting glucose alone did not predict clustering of risk factors, which may indicate that insulin resistance was compensated for by increased insulin secretion.