A case-control study of physical activity and non-insulin dependent diabetes mellitus (NIDDM): The San Luis Valley Diabetes Study

PURPOSE: The purpose of this study was to examine the association between p hysical activity and noninsulin dependent diabetes mellitus (NIDDM). METHODS: We conducted a population-based case-control study in Hispanic and non-Hispanic white men and women, ages 20-74. A total of 167 cases with NI DDM and 1100 controls with normal glucose tolerance were included. All subj ects completed an oral glucose tolerance test. RESULTS: Persons with recently diagnosed NIDDM reported significantly Lower levels of physical activity than control subjects. For total metabolic uni ts, the odds ratio for subjects in the highest tertile compared to those in the lowest tertile was 0.60 (95% confidence interval (CI) = 0.37-0.98) aft er adjusting for age, sex, ethnicity, and family history of diabetes. The a djusted odds ratio for persons reporting high levels of vigorous activity ( at least three times per week for 20 minutes) was also Less than 1, but was not statistically significant (odds ratio (OR) = 0.73, 95% CI = 0.47-1.14) . Similar adjusted odds ratios were observed for high versus low levels of self-assessed work activity (OR = 0.50, 95% CI = 0.34-0.74) and leisure rim e physical activity (OR = 0.62, 95% CI = 0.44-0.90). Further adjustments fo r body mass index attenuated the strength of the association between physic al activity and NIDDM. This is consistent with the hypothesis that obesity is one consequence of physical inactivity that puts individuals at increase d risk for NIDDM. The association of physical activity and NIDDM was strong er in Hispanic than in non-Hispanic white subjects, although this differenc e was not statistically significant. CONCLUSIONS: High levels of physical activity are associated with lower odd s of NIDDM and this relationship may be stronger in Hispanic subjects. Ann Epidemiol 2001;11:320-327. (C) 2001 Elsevier Science Inc.. All rights reser ved.