Original articleA Case-Control Study of Physical Activity and Non-Insulin Dependent Diabetes Mellitus (NIDDM): The San Luis Valley Diabetes Study
Introduction
Since Hispanic populations in Colorado (1), Texas 2, 3, and New Mexico (4) have a 2–5 times higher rate of non-insulin dependent diabetes mellitus (NIDDM) than non-Hispanic white (NHW) populations, studies are needed to determine potential modifiable risk factors in these populations with the ultimate goal of identifying preventive measures. Physical activity is one of few such modifiable environmental risk factors that could be related to the risk of NIDDM.
Populations undergoing rapid westernization usually have decreases in levels of habitual physical activity, which on an ecological 5, 6 or individual level 7, 8, 9 have been associated with higher NIDDM occurrence. Several retrospective studies have found a consistently lower risk for NIDDM among persons with greater activity in populations as diverse as Finns (10), U.S. Whites 11, 12, 13, Pima Indians (14) Japanese-Americans (15), Indians and Creoles on the island of Mauritius (16), and Tanzanian Hindus (17). Prospective studies have also been published reporting lower NIDDM risk among subjects with higher baseline activity 18, 19, 20, 21, 22, 23. Most studies show a 20–60% reduction in the risk of NIDDM associated with higher levels of activity. However, there have been only two preliminary explorations of the role of physical activity and NIDDM among U.S. Hispanic populations 24, 25.
In this paper we describe the results of a case-control study which examined the association between physical activity and NIDDM in Hispanic and NHW subjects. Since physical activity habits may change after diagnosis of NIDDM, results from known diabetic cases may be biased. For this reason, we also included previously undiagnosed diabetic subjects who were unaware of their glucose tolerance status at the time of interview.
Section snippets
Methods
The San Luis Valley Diabetes Study is a population-based study of risk factors and complications of NIDDM in Hispanic and NHW men and women, ages 20–74, in two counties in southern Colorado. Detailed study methods have been published previously (1). Clinic visits for the subjects in this report were conducted between May 1984 and August 1988. Subjects with diabetes, previously diagnosed in the community, were identified by retrospective review of medical records in local practices, ongoing
Results
The gender and ethnic distributions of cases and controls are shown in Table 1. Other descriptive characteristics of cases and controls are shown in Table 2 for males and Table 3 for females. A similar pattern is seen for both the previously undiagnosed and recently diagnosed cases compared to controls. Both groups of diabetic subjects had a significantly higher mean age, BMI, waist circumference, subscapular skinfold, and subscapular/triceps ratio compared to controls. Self-reported family
Discussion
As part of the San Luis Valley Diabetes Study, we examined the relationship between physical activity and NIDDM in two groups of diabetics compared to control subjects with normal glucose tolerance. These data suggest that with adjustment for sex, ethnicity, and family history, persons with higher levels of physical activity were 25–50% less likely to have NIDDM. After controlling for BMI, the association of physical activity and NIDDM became non-significant in most models. Physical activity
Selected Abbreviations and Acronyms
BMI = body mass index
METS = total metabolic units
NHW = non-Hispanic white
NIDDM = non-insulin-dependent diabetes mellitus
OGTT = oral glucose tolerance test
WHO = World Health Organization
References (53)
- et al.
Epidemiology of factors related to self-reported diabetes among adults
Am J Prev Med.
(1986) - et al.
Physical activity and incidence of non-insulin-dependent diabetes mellitus in women
Lancet.
(1991) - et al.
Incidence and predictors of diabetes in Japanese-American menThe Honolulu heart project
Ann Epidemiol.
(1995) - et al.
Physical activity measures compared in a biethnic rural populationThe San Luis Valley Diabetes Study
Am J Clin Nutr.
(1991) - et al.
The San Luis Valley diabetes studyMethods and prevalence of non-insulin-dependent diabetes mellitus (NIDDM) in a biethnic Colorado population
Am J Epidemiol.
(1989) Diabetes among Mexican Americans in Starr County, Texas
Am J Epidemiol.
(1983)- et al.
Does obesity explain excess prevalence of diabetes among Mexican-Americans? Results of the San Antonio Heart Study
Diabetologia.
(1983) - et al.
Diabetes, gallbladder disease, obesity, and hypertension among Hispanics in New Mexico
Am J Epidemiol.
(1988) - et al.
The prevalence of diabetes in the rural and urban Polynesian population of Western Samoa
Diabetes.
(1981) - et al.
The influence of variation in obesity in the sex difference in the prevalence of abnormal glucose tolerance in Tuvalu
N Z Med J.
(1981)