Aims/hypothesis To assess the impact of impaired insulin secretion (IIS) and insulin resistance (IR) on type 2 diabetes incidence in a Japanese population. Methods This 4 year cohort study included 3,059 participants aged 30-69 without diabetes at baseline who underwent comprehensive medical check-ups between April 2006 and March 2007 at Saku Central Hospital. Based on their insulinogenic index and HOMA-IR values, participants were classified by the criteria of the Japan Diabetes Society into four categories: normal; isolated IIS (i-IIS); isolated IR (i-IR); and IIS plus IR. They were followed up until March 2011. The incidence of type 2 diabetes was determined from fasting and 2 h post-load plasma glucose concentrations and from receiving medical treatment for diabetes. Results At baseline, 1,550 individuals (50.7%) were classified as normal, 900 (29.4%) i-IIS, 505 (16.5%) i-IR, and 104 (3.4%) IIS plus IR. During 10,553 person-years of follow-up, 219 individuals developed type 2 diabetes, with 126 (57.5%) having i-IIS at baseline. Relative to the normal group, the multivariable-adjusted HRs for type 2 diabetes in the i-IIS, i-IR and IIS plus IR groups were 8.27 (95% CI 5.33, 12.83), 4.90 (95% CI 2. 94, 8.17) and 16.93 (95% CI 9.80, 29.25), respectively. The population-attributable fractions of type 2 diabetes onset due to i-IIS, i-IR, and IIS plus IR were 50.6% (95% CI 46.7%, 53.0%), 14.2% (95% CI 11.8%, 15.6%) and 12.9% (95% CI 12.3%, 13.2%), respectively. Conclusions/interpretation Compared with IR, IIS had a greater impact on the incidence of type 2 diabetes in a Japanese population.

The prevalence of both hypertension and diabetes mellitus is increasing worldwide. Both diseases lead to severe complications such as cardiovascular and chronic kidney diseases, which increase the risk of death over a long period of time. Therefore, the prevention and aggravation of hypertension and diabetes mellitus are major challenges. Because few review articles have focused on the epidemiological perspective of hypertension and diabetes mellitus, we reviewed major observational studies mainly from Japan and from Western countries that have reported on the prevalence of hypertension and diabetes mellitus, the binominal risk of hypertension and diabetes mellitus, and the risk of their coexistence. Our investigation found that approximately 50% of diabetic patients had hypertension, and approximately 20% of hypertensive patients had diabetes mellitus. Those with either hypertension or diabetes mellitus had a 1.5- to 2.0-fold higher risk of having both conditions. These results were similar for both Japan and Western countries. Although comparing the results between Japan and Western countries was difficult because the risks were estimated using widely varying statistical analyses, it was revealed that the coexistence of hypertension and diabetes mellitus certainly increased the risk of complications regardless of the country. The definition, prevalence and medical treatment of hypertension and diabetes mellitus will change in the future. For early intervention based on the latest evidence to prevent severe complications, it is important to accumulate epidemiological knowledge of hypertension and diabetes mellitus and to update the evidence for both Japan and other countries.

Objective: To investigate the association between visceral fat area (VFA) and metabolic syndrome (Mets) among normal weight Japanese.Design: A cross-sectional study. Setting: The health check-up centre of the Takeda Hospital group in Kyoto, Japan.Methods: This study involved 1674 men and 1448 women aged 30-74 years who underwent medical check-ups in 2012 in the health check-up centre. They were stratified by Body Mass Index (BMI cut-off for obesity is set at 23.0 kg/m 2 for Asians): normal weight 18.5-22.9 kg/m 2 or higher weight ≥23.0 kg/m 2 . The age-adjusted ORs of the 2nd to 4th groups of sexspecific VFA quartiles compared with the 1st quartile for a Mets component clustering were estimated. The clustering was having two or more of the following factors: high blood pressure, high fasting blood glucose (FBG), low high-density lipoprotein cholesterol (HDL-C) and high triglycerides. Statistical analyses were conducted in 2016.