Poor fitness tied to insulin resistance in otherwise healthy people
Researchers performed a cross-sectional analysis of 19,263 women and 48,433 men, none of whom had a history of diabetes or cardiovascular disease. Cardiorespiratory fitness was measured through an exercise treadmill test. Insulin resistance was evaluated according to impaired fasting glucose and elevated levels of fasting triglycerides.
In both men and women, markers of insulin resistance coincided with old age, an elevated blood pressure, high body mass index (BMI), smoking, and low fitness.
Multiple logistic regression analysis found that among normal-weight men, having poor fitness almost tripled the risk of having both markers of insulin resistance (odds ratio [OR], 2.8, 95 percent confidence interval [CI], 2.1–3.6; p<0.001). In women of normal weight, this effect was slightly weaker, but nevertheless significant (OR, 2.2, 95 percent CI, 1.4–3.6; p=0.001).
Generally, this effect weakened as BMI status worsened but remained significant. In overweight men (OR, 2.4, 95 percent CI, 2.1–2.7; p<0.001) and women (OR, 2.1, 95 percent CI, 1.5–3.0; p<0.001), poor fitness increased the risk of having both markers for insulin resistance. The same was true for obese participants (men: OR, 1.7, 95 percent CI, 1.5–2.0; women: OR, 1.9, 95 percent CI, 1.4–2.5; p<0.001).
“Future work will be necessary to assess the longitudinal relationship between cardiorespiratory fitness and insulin resistance. Finally, additional work is needed to better understand fitness and insulin resistance in non-white populations,” researchers said.