Mariko Kawaharada

Short Sleep Duration and Poor Sleep Quality Increase the Risk of Diabetes in Japanese Workers With No Family History of Diabetes

OBJECTIVE To investigate whether a difference in the risk for diabetes exists in Japanese workers with regard to sleep duration/quality and the presence or absence of a family history of diabetes (FHD). RESEARCH DESIGN AND METHODS The researchers conducted a prospective, occupational-based study of local government employees in Sapporo, Japan. Between April 2003 and March 2004, 3,570 nondiabetic participants, aged 35–55 years, underwent annual health checkups and completed a self-administered questionnaire that included information on sleep duration/quality and FHD at baseline. Having diabetes was defined as taking medication for diabetes or a fasting plasma glucose level of ≥126 mg/dL at follow-up (2007–2008). RESULTS A total of 121 (3.4%) new cases of diabetes were reported. In multivariate logistic regression models of workers without an FHD, and after adjustment for potential confounding factors, the odds ratio (95% CI) for developing diabetes was 5.37 (1.38–20.91) in those with a sleep duration of ≤5 h compared with those with a sleep duration of >7 h. Other risk factors were awakening during the night (5.03 [1.43–17.64]), self-perceived insufficient sleep duration (6.76 [2.09–21.87]), and unsatisfactory overall quality of sleep (3.71 [1.37–10.07]). In subjects with an FHD, these associations were either absent or weaker. CONCLUSIONS The current study shows that poor sleep is associated with a higher risk of developing diabetes in workers without an FHD. Promoting healthy sleeping habits may be effective for preventing the development of diabetes in people without an FHD.

Metabolic syndrome, C-reactive protein and increased arterial stiffness in Japanese subjects

The aim of this study was to investigate whether the metabolic syndrome (MS) was associated with an elevated level of C-reactive protein (CRP) and increased arterial stiffness, and to clarify whether combined MS and CRP data had a stronger relation to arterial stiffness than did MS data alone. Brachial-ankle pulse wave velocity (baPWV), CRP, and conventional risk factors were evaluated in 3,412 men and 854 women. Adjusted mean values of baPWV in men with 0, 1, 2, and ≥3 components were 1,309, 1,372, 1,422, and 1,462 cm/s, respectively (p for trend <0.001). Adjusted mean values of baPWV in women with 0, 1, 2, and ≥3 components were 1,212, 1,292, 1,357, and 1,391 cm/s, respectively (p for trend <0.001). Adjusted geometric mean concentrations of CRP in men with 0, 1, 2, and ≥3 components were 0.036, 0.049, 0.059, and 0.076 mg/dl, respectively (p for trend <0.001). Adjusted geometric mean concentrations of CRP in women with 0, 1, 2, and ≥3 components were 0.023, 0.030, 0.057, and 0.077 mg/dl, respectively (p for trend <0.001). In analyses of adjusted mean values of baPWV according to the number of MS components and according to CRP levels within or without top quartile levels, the p value for the trend was significant (<0.001) in both men and women but, in post hoc analyses, comparing high and low CRP levels in each MS component–number group, no significant difference was found. These results suggest that, for prediction of increased arterial stiffness, combining MS and CRP data has little additive effect compared to the use of MS data alone.

Effects of the Interaction between Interleukin-6 -634C/G Polymorphism and Smoking on Serum C-Reactive Protein Concentrations.

Smoking and interleukin-6 (IL-6) are major factors in inflammation. The aim of this study was to investigate whether or not the IL6 −634C/G polymorphism (rs1800796) and its interaction with smoking influence serum C-reactive protein (CRP) concentrations. The subjects were 347 Japanese male employees of a transit company. CRP and conventional cardiovascular risk factors were evaluated. IL6 −634C/G polymorphisms were genotyped by allelic discrimination using fluorogenic probes and the 5′ nuclease assay. The mean values of CRP were significantly higher in current smokers than in nonsmokers after adjustment for age, body mass index (BMI), systolic blood pressure, total cholesterol, log triglycerides, high-density lipoprotein cholesterol (HDL-C), fasting glucose, and drinking habit (p=0.011). Comparison of three genotypes revealed significant interaction between smoking and the IL6 −634C/G genotype manifested by CRP concentrations (p=0.007) after the adjustments cited above. After stratification by smoking status, CRP differed significantly among IL6 −634C/G genotypes groups in nonsmokers (p=0.010, p for trend=0.007), whereas no significant difference was found in current smokers. Comparison between −634C/C and C/G+G/G groups revealed also a significant interaction between smoking and the IL6 −634C/G genotype (p=0.007). These findings suggest that the impact of the −634G allele on CRP elevation is greater in nonsmokers than in current smokers. Since gene-environment interactions have been insufficiently examined, further studies are required to clarify their effect on inflammation, including CRP elevation.

Relationship of socioeconomic status to C-reactive protein and arterial stiffness in urban Japanese civil servants.

This study investigates whether the two socioeconomic status indicators, educational level and employment grade, are associated with C-reactive protein (CRP) levels and arterial stiffness among Japanese urban civil servants. Brachial-ankle pulse-wave velocity (baPWV) as an indicator of arterial stiffness, CRP, occupational stress and conventional risk factors were evaluated in 3412 men and 854 women. Although the socioeconomic gradient showed a significant association with the CRP levels in men after adjustment for age, the significance disappeared after multivariate adjustment, whereas in women, the socioeconomic gradient showed no significant association with the CRP levels. In men, educational level was significantly associated with the baPWV value after adjustment for conventional risk factors, CRP and occupational stress (P for trend <0.0001). With regards to employment grade, only low-level non-manual workers had a significantly lower baPWV value as compared to manual workers at a fully adjusted model, and trend significance disappeared. However, in women, neither educational level nor employment grade was associated with the baPWV value. In summary, the socioeconomic gradient, especially the educational level, was significantly inversely related to the baPWV value in men. In women, the socioeconomic gradient was not related to the baPWV value. An inverse relationship between the socioeconomic gradient and CRP levels was found in men only after age adjustment. We suggest that because the educational level is an important aspect in the adolescent environment and hence might influence the future lifestyle, early health education should be provided to prevent an unfavourable lifestyle and atherosclerotic diseases in later life.