Longitudinal association of sedentary time with diabetes mellitus and markers of glucose metabolism in middle-aged and older adults: The Hisayama Study

Sedentary behavior is known to have adverse health effects in regard to lifestyle-related diseases, such as diabetes. Most previous studies used self-report questionnaires for measuring sedentary behavior, which are subject to recall bias, but accelerometers are increasingly being used in epidemiological studies to estimate sedentary time more reliably. A meta-analysis integrating studies using accelerometers reported a positive association between sedentary time and diabetes or markers of glucose metabolism1. However, most of the included studies were cross-sectional studies. Two other analyses prospectively investigated the relationship between sedentary time and diabetes, and found no statistically significant associations2, 3, although their participants were limited to relatively young adults2 or postmenopausal women3. Using data from a population-based study, the Hisayama Study, we previously reported a cross-sectional relationship between sedentary time and diabetes or homeostasis model assessment of insulin resistance (HOMA-IR)4. The aim of the present study was to prospectively examine these associations based on 5-year follow-up data. In total, 1,329 community-dwelling non-diabetes individuals aged 40–79 years who participated in physical examinations in 2012 and 2017 with valid accelerometer measurements were included in the present study. Assessment of sedentary time was reported previously4. Incident diabetes was defined as glycated hemoglobin ≥48 mmol/mol, fasting plasma glucose ≥7.0 mmol/L, 2-h post-load plasma glucose ≥11.1 mmol/L or use of antidiabetic drugs at the follow-up examination in 2017. Odds ratios for developing diabetes were calculated using logistic regression models. Associations between sedentary time and changes in glucose metabolism markers were examined using analyses of covariance. As shown in Table 1, 106 participants developed diabetes. There was no significant association between sedentary time and 5-year incidence of diabetes among overall participants. In the subgroup analysis of HOMA-IR levels, however, the odds ratio for developing diabetes increased significantly with longer sedentary time in those with HOMA-IR >1.6. Longer sedentary time was significantly associated with greater 5-year increase in fasting insulin and HOMA-IR. The present study did not find a significant relationship between sedentary time and incident diabetes among overall participants, but there was a significant relationship in those with insulin resistance, suggesting that the influence of sedentary behavior on diabetes progression might vary depending on baseline levels of muscle quality, especially the different muscle fiber types, and quantity. The present study also showed that sedentary time was associated with 5-year changes in HOMA-IR, which supported our previous findings4. In contrast, Barone Gibbs et al.2 reported no significant association between sedentary behavior and 5-year HOMA-IR change, but their study included relatively younger participants (aged 38–50 years), which might have resulted in a slower rate of increase in HOMA-IR. There were several limitations to the present study, including limited ethnic group and small number of individuals with incident diabetes, especially in the low HOMA-IR group. In addition, as sedentary time was measured only at baseline, its changes during follow up could not be considered. However, the present findings suggest that prolonged sedentary behavior might cause insulin resistance and subsequent incident diabetes in a high-risk population, and underscore the importance of reducing sedentary time. The authors thank the residents of the town of Hisayama for their participation in the survey. This study was supported in part by the Ministry of Education, Culture, Sports, Science and Technology of Japan (JSPS KAKENHI Grant Numbers JP21H03200, JP21K07522, JP21K11725, JP21K10448, JP22K07421, JP22K17396, JP23K09692, JP23K09717, JP23K16330, JP23K06787 and JP23K09060); by Health and Labor Sciences Research Grants of the Ministry of Health, Labor and Welfare of Japan (JPMH23FA1006 and JPMH23FA1022); by the Japan Agency for Medical Research and Development (JP23dk0207053 and JP23km0405209); and by a Japan Science and Technology Agency (JST) Grant (JPMJPF2210). The authors declare no conflict of interest. Approval of the research protocol: Kyushu University Institutional Review Board for Clinical Research (Approval No. 2023-56). Informed consent: Written informed consent was obtained from the study participants. Registry and the registration no. of the study: N/A. Animal studies: N/A.