Impact of longitudinal status change in metabolic syndrome defined by two different criteria on new onset of type 2 diabetes in a general Japanese population: the Tanno-Sobetsu Study

Background: We investigated the effect of longitudinal status change in metabolic syndrome (MetS) assessed by two different criteria on new onset of type 2 diabetes (NODM) in a Japanese population. Methods: The participants were 827 non-diabetic citizens who had undergone medical examinations in 1994 and 2003 or 2004. We used two different criteria of MetS: the interim criteria by 6 institutions (MetS-INT) and Japanese criteria (MetS-JP). According to the interim criteria, individuals defined as having MetS have any three of the following five components of MetS: obesity, hyperglycemia, high blood pressure, hypertriglyceridemia and low HDL cholestero-lemia. According to the Japanese criteria, individuals defined as having MetS must have abdominal obesity plus any two of the following three factors; hyperglycemia, high blood pressure and dyslipidemia (hypertriglyceridemia and/or low HDL-cholesterolemia). According to the status change in MetS, participants were divided into four groups: a non-MetS to non-MetS group, a non-MetS to MetS group, a MetS to non-MetS group and a MetS to MetS group. We calculated odds ratios of these four groups for NODM. Results: NODM occurred in 65 participants. The odds ratios for NODM were 4.86, 4.97 and 7.50 in the non-MetS-INT to MetS-INT group, MetS-INT to non-MetS-INT group and MetS-INT to MetS-INT group, respectively. On the other hand, the odds ratios were 4.28 and 15.55 in the non-MetS-JP to MetS-JP group and MetS-JP to MetS-JP group, respectively. After adjustment for high fasting plasma glucose at baseline, magnitude of the odds ratio of MetS to MetS group was larger in the Japanese criteria group than in the interim criteria group. Conclusions: Determining the status of MetS routinely and paying attention to status change in MetS may be important for prevention of type 2 diabetes. MetS defined by the criteria which includes obesity as a prerequisite component may be a stronger risk for type 2 diabetes than MetS defined by the criteria which includes obesity as one of components.