New “Pre-diabetes” Category and the Metabolic Syndrome in Japanese

BACKGROUND: Recently, impaired fasting glucose (IFG) was redefined as fasting plasma glucose of 100-125 mg/dl, and individuals with IFG and/or impaired glucose tolerance (IGT) were referred to as having "pre-diabetes". However, there is a lack of data using the new definition of IFG and "pre-diabetes". OBJECTIVE: The aim of this study was to examine associations of the metabolic syndrome components with the new "pre-diabetes" category in relatively lean Japanese. METHODS: Six hundred and sixty-one Japanese study participants underwent a 75 g oral glucose tolerance test. They were classified into three groups-normal (n=225), pre-diabetes (n=308), and diabetes (n=128). The metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III, as modified for waist circumference criteria by the Regional Office for the Western Pacific Region of WHO. RESULTS: Prevalence of the metabolic syndrome in each group was 10.7%, 27.9%, and 53.9%, respectively. Of the metabolic syndrome components, the OR for prevalent pre-diabetes was 2.00 (95% CI, 1.73-2.31, p<0.001) for fasting glucose, 1.93 (95% CI, 1.54-2.42, p<0.001) for waist circumference, and 1.36 (95% CI, 1.10-1.68, p=0.005) for triglycerides. Similar associations were found in prevalent diabetes. Insulin resistance assessed using Stumvoll's index was significantly associated with both pre-diabetes and diabetes. CONCLUSION: Pre-diabetes and the metabolic syndrome frequently coexist in relatively lean Japanese. This association seems to link with abdominal adiposity and insulin resistance.