Cardiorespiratory fitness appears to be correlated with clinical markers of glycemic control, with high HbA1c, high fasting glucose and impaired oral glucose tolerance related to lower cardiorespiratory fitness levels, according to recent findings.
Moreover, cardiorespiratory fitness also appears to be associated with pancreatic beta-cell insulin secretory compensation for changing insulin sensitivity, the researchers wrote.
In the study, Thomas P. J. Solomon, PhD, of the University of Copenhagen in Denmark, and colleagues from institutions in the United States evaluated 313 participants stratified by glucose tolerance status based on their 2-hour glucose on an oral glucose tolerance test (OGTT).
Participants were measured for height, weight, estimated whole-body adiposity, HbA1c, total cholesterol, triglycerides and fasting glucose with OGTT. Insulin sensitivity during OGTT was calculated using a previously validated method, and the researchers also measured the glucoestimated insulin secretion and the disposition index, a measure of glucose disposal that estimated pancreatic beta-cell insulin secretion compensation for changing insulin sensitivity during OGTT.
The participants performed an exercise test to ascertain cardiorespiratory fitness during comprehensive incremental workload exercise. The researchers assessed the relationships between cardiorespiratory fitness and clinical markers of glycemic control.
The researchers found that low cardiorespiratory fitness was correlated with high HbA1c (r = -0.33), high fasting plasma glucose (r = -0.34), high 2-hour OGTT (r = -0.33), low insulin sensitivity during OGTT (r = 0.73), high early-phase glucoestimated insulin secretion (r = -0.34) and high late-phase glucoestimated insulin secretion (r = -0.36). Moreover, an association was identified between low cardiorespiratory fitness and low early- and late-phase disposition index (both r = 0.41). Notably, the associations between cardiorespiratory fitness and either glycemic control or late-phase glucoestimated insulin secretion were attenuated across the continuum of glucose tolerance.
“In conclusion, our study has advanced the prior knowledge that high cardiorespiratory fitness is associated with good glycemic control by showing that [cardiorespiratory fitness] is also positively associated with the disposition index in a cohort of adults representing the entire glucose tolerance continuum,” the researchers wrote. “While the large contribution of body weight and BMI must not be ignored, these findings are clinically significant because they also highlight the importance of an individual’s cardiorespiratory fitness level in relation to the fundamental pathophysiological cause of hyperglycemia-related chronic disease.” – by Jennifer Byrne
Disclosure: The study was funded in part by a Paul Langerhans Program grant from the European Foundation for the Study of Diabetes/Amylin Pharmaceuticals, Inc.