Inter-relationships between the severity of metabolic syndrome, insulin and adiponectin and their relationship to future type 2 diabetes and cardiovascular disease

BACKGROUND: The severity of the metabolic syndrome (MetS) is related to future incidence of type 2 diabetes (T2DM) and cardiovascular disease (CVD). However, the relationship between MetS severity and levels of fasting insulin and adiponectin-markers of insulin resistance-is unclear. METHODS: We used linear and logistic regression to analyze data from 711 participants of the Princeton Lipid Research Cohort with information regarding levels of insulin, adiponectin and MetS severity during 1998-2003 (mean age 39.5 years); 595 participants had MetS severity data from childhood (1973-1976, mean age 12.9 years) and 417 had updated disease status from 2010 to 2014 (mean age 50.9 years). RESULTS: Childhood MetS Z-scores were positively associated with adult insulin levels (P < 0.001) and negatively associated with adiponectin levels (P = 0.01). In individual analyses, higher insulin levels and MetS Z-score as adults were related to higher odds of incident diabetes and CVD over the next 11.2 years (all P < 0.001), whereas lower adiponectin levels were only related to odds of future T2DM (P < 0.0001). In a model including insulin, adiponectin and MetS Z-score, adiponectin was not linked to future disease; both insulin (P = 0.027) and MetS Z- score (P = 0.002) were related to risk of future T2DM, while only MetS Z- score was related to future CVD (P < 0.001). CONCLUSIONS: The severity of MetS exhibits long-term links to levels of insulin and adiponectin, suggesting potential genetic and environmental influences on insulin resistance over time. As a long-term predictor of T2DM and CVD, the severity of MetS exhibited consistent independent correlations. This supports clinical utility in evaluating MetS severity as a predictor of risk for future disease.