Clustering of components of the metabolic syndrome and risk for development of type 2 diabetes in Japanese male office workers.

To investigate the effects of the clustering of components of the metabolic syndrome (MS) on development of diabetes, we examined 3298 Japanese male office workers aged 35-59 years who did not have type 2 diabetes (a fasting plasma glucose level of > or =7.0 mmol/l or receipt of hypoglycemic medication) or a history of cardiovascular disease. Fasting plasma glucose levels were measured at periodic annual health examinations from May 1994 through May 2001. After adjustment for potential risk factors for diabetes, the multivariate-adjusted relative risk of type 2 diabetes compared with the subjects without components of the MS was 1.58 (95% CI: 1.08-2.32), 2.48 (95% CI: 1.69-3.63), 3.10 (95% CI: 2.05-4.68), and 5.22 (95% CI: 3.49-7.83) (P-value for trend <0.001) for those with 1, 2, 3, and > or =4 components, respectively. Even after the subjects were stratified according to fasting plasma glucose level, the clustering of components of the MS was associated with an increased risk of type 2 diabetes for subjects in all three categories of low-normal fasting glucose (a fasting plasma glucose level of <5.1 mmol/l), high-normal fasting glucose (a fasting plasma glucose level of 5.0-6.0 mmol/l), and impaired fasting glucose (a fasting plasma glucose level of 6.1-6.9 mmol/l). These results indicate that clustering of components of the MS associated with diabetes precedes an increase in the risk of type 2 diabetes in Japanese men.