Cardiorespiratory Fitness, BMI Linked to Risk of Type 2 Diabetes in Women

Low cardiorespiratory fitness, as measured by a treadmill exercise test, and high body mass index (BMI) are independently associated with incident type 2 diabetes in women, according to study findings.

"Obesity and physical inactivity are two major contributors to type 2 diabetes in men and women," write Dr. Xuemei Sui, of the University of South Carolina, Columbia, and colleagues. "Because women newly diagnosed with diabetes have a higher relative risk for cardiovascular disease death than men with diabetes, it is important to investigate the associations among obesity, physical activity, and the risk of developing type 2 diabetes in women."

The researchers’ study involved an observational cohort of 6249 women between the ages of 20 and 79 years who were free of cardiovascular disease, cancer, and diabetes at baseline. "CRF (cardiorespiratory fitness) was assessed as the duration of a symptom-limited maximal treadmill exercise test," the team reports, and the women were categorized into thirds — low, middle and high — based on age-specific treadmill time.

A total of 143 cases of type 2 diabetes occurred during a 17-year follow-up period.

After adjusting for a number of covariables including BMI, women in the middle and upper thirds of CRF had significantly lower risks of diabetes compared to the least fit third (hazard ratios 0.86 and 0.61 for the middle and upper thirds, respectively; p = 0.03).

For BMI, the multivariate (including CRF) adjusted HRs for overweight and obese subjects were 2.34 and 3.70, respectively, compared with normal-weight individuals.

In an analysis examining the combined effects of CRF and BMI on diabetes risk, the researchers found that while fitness had a protective effect in overweight/obese individuals, it did not eliminate their increased risk.

Dr. Sui said,  "These findings underscore the critical importance of promoting regular physical activity and maintaining normal weight for diabetes prevention."

"Given the rapidly growing population prevalence of diabetes, the small improvements in physical activity over the past decade, and the continuing rise in obesity rates, we believe health professionals should consider the potential benefits of greater fitness and aggressively counsel their sedentary obese patients to become more physically active and improve their fitness as a cornerstone of diabetes prevention," Dr. Sui said.

"Our next step," the researcher added, "is to examine the association between cardiorespiratory fitness, body mass index, and all-cause mortality in women who have impaired fasting glucose and undiagnosed diabetes to clarify if lower fitness and higher body weight have great impact on survival in these high-risk women."

Diabetes Care 2008;31:550-555.

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DID YOU KNOW:
It’s Official, Walking is now the official state exercise in Maryland. The bicycling lobbyists got caught with their kickstands down.  There are a couple of dozen things that are designated as Maryland’s official something-or-other, from trees to flowers, sports to fish. Yesterday, Gov. Martin O’Malley signed into law one more – walking is now the official state exercise.

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