Objective To examine whether aging itself affects insulin resistance (IR) and insulin secretion in the general Japanese population. Methods This study included data for 2,324 men and 1,472 women 30-79 years of age without diabetes who participated in a general health checkup program. The effects of age on homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of β-cell function (HOMA-B) were examined using a linear regression model. Logistic regression models were used to identify clinical characteristics related to age. Multiple regression analyses using a stepwise form were performed to examine factors, including age, possibly affecting HOMA-IR and HOMA-B. Results The fasting plasma glucose (FPG) levels increased with age in both sexes, whereas the body mass index (BMI) and HOMA-B decreased with increasing age in men and the BMI increased with age in women. The HOMA-IR increased with increasing age in postmenopausal women. The proportion of physically active subjects increased in both sexes, and the proportion of current smokers decreased with age in men and postmenopausal women. The proportion of regular drinkers increased, and the proportion of subjects with a family history of diabetes decreased with age in men. The stepwise multiple regression analysis showed that age was inversely associated with the HOMA-B in both sexes and positively associated with the HOMA-IR in men and postmenopausal women. However, the BMI had the largest impact on the HOMA-IR and HOMA-B in both sexes. Conclusion Age-related increases in the glucose levels in Japanese men and women may be associated with impaired insulin secretion. As a result, a sex difference was observed regarding the impact of aging on IR.
Background/Objectives: Non-alcoholic fatty liver disease (NAFLD) is a common condition, in which abnormal amounts of triglycerides accumulate in hepatocytes and is closely related to cardiovascular diseases and diabetes. Dietary fats contribute 15% of fat accumulation in the liver and regulate hepatic lipid metabolism. The supplementation of n-3 polyunsaturated fatty acids (n-3 PUFAs) improves NAFLD. The aim of this study is to assess the cross-sectional association between dietary n-3 PUFAs and NAFLD in Japanese men and women. Subjects/Methods: Participants were middle-aged, apparently healthy, 296 men and 496 women, who did not drink alcohol and who participated in a general health check-up program. Dietary information from the previous month was obtained by the brief-type self-administered diet history questionnaire. NAFLD was diagnosed if abdominal ultrasonography revealed the presence of fatty liver. Results: The prevalence of NAFLD was 45.3% in men and 17.5% in women. In comparison with the first tertile, multivariate adjusted odds ratios (95% confidence intervals) for the presence of NAFLD in the second and third tertiles for men taking eicosapentaenoic acid (EPA) were 0.59 (0.31-1.14) and 0.45 (0.23-0.90), respectively, (P for linear trend ¼ 0.024), and the multivariate adjusted odds ratios (95% confidence intervals) for the presence of NAFLD in the second and third tertiles for men taking EPA þ docosahexaenoic acid (DHA) were 0.44 (0.23-0.86) and 0.48 (0.24-0.95), respectively, (P for linear trend ¼ 0.035). However, there was no significant relation between NAFLD and each of these nutrients in women. Conclusions: Dietary EPA and EPA þ DHA may be independent and preventive nutrients for NAFLD in Japanese men.
Higher BMI and triglyceride levels were positively associated with prevalent impaired glucose regulation in all geographical regions. There were geographic differences in the association between impaired glucose regulation and blood pressure and lipids, probably reflecting environmental and genetic factors.
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