Low vital capacity is associated with diabetes despite inverse relationships with metabolic risk factors in lean Japanese men.

Background: There is no study examining the relationships between vital capacity and diabetes or metabolic risk factors in lean subjects.

Methods: Cross-sectional relationships between % vital capacity (%VC) and diabetes and metabolic risk factors were examined in Japanese subjects using medical check-up data from 2,079 men and 1,215 women. Subjects were divided into lean (BMI <23 kg/m(2)) and obese (BMI >or=23 kg/m(2)) groups and then subdivided into lower %VC (or=96%) subgroups by gender. Metabolic risk factors and prevalence of diabetes and MS were compared between the subjects in each group, and then excluding current smokers and between subjects with the lowest quartile of %VC and those with the highest quartile of %VC in the lean men group. Spearman's correlation coefficients between %VC and metabolic risk factors were calculated separately in obese subjects and in lean subjects by gender.

Results: The prevalence of diabetes, but not metabolic syndrome, was significantly higher in subjects with the lower %VC than in those with the higher %VC in the lean men despite the fact that age, obesity parameters, systolic and diastolic blood pressures were significantly lower in subjects with the lower %VC than in those with the higher %VC and triglycerides, high-density lipoprotein cholesterol, high-sensitivity C-reactive protein, white blood cell count, and heart rate were not significantly different between the two groups.

Conclusion: Low vital capacity was significantly associated with diabetes in lean Japanese men despite inverse relationships with metabolic risk factors.