Diabetes incidence for all possible combinations of metabolic syndrome components.

Aims: Because metabolic syndrome (MetS) is defined as any three of five criteria, not all persons with MetS have the same risk factors. Whether the combinations of criteria confer equal diabetes risk is unknown.

Methods: We identified 58,056 non-diabetic adults age >=30 with all MetS components measured in 2003-2004. We estimated age- and sex-adjusted diabetes incidence over 5 years for all possible combinations of MetS components.

Results: The overall incidence rate of diabetes was 12.5/1000 person-years (95% CI 12.1-12.9). Although incidence increased with the MetS factor count, incidence varied by >9-fold in patients with 3 risk factors, >5-fold in patients with 4 factors, and >54-fold in patients with <3 factors. All two-factor combinations that included hyperglycemia had higher incidence rates than three- or four-factor combinations that did not. For example, incidence in patients with only hyperglycemia and obesity was 21.7/1000 person-years (95% CI 17.4-27.1), compared to 11.4 (9.8-13.4) among those with four components without hyperglycemia.

Conclusions: Diabetes risk increases exponentially with MetS factor count, but varies substantially depending upon which factors are present. Hyperglycemia, regardless of the presence of MetS, is a much stronger predictor of incident diabetes than MetS without hyperglycemia.