Relationships Between Glycemic Control and Cardiovascular Fitness

Introduction: Diabetes is a serious health problem affecting approximately 29.1 million individuals in the United States. Another 86 million have prediabetes. The development and implementation of lifestyle modifications such as physical activity for these persons are among the most effective methods for prevention and treatment. Objective: The aim of this study was to examine relationships between glycemic control (HbA1c) and cardiovascular fitness (peak maximal oxygen uptake [VO2 peak] and ventilatory threshold [VT]) in overweight/obese subjects with and without type 2 diabetes (T2DM). In addition, the influences of body mass index (BMI) and insulin sensitivity (homeostasis model assessment [HOMA %S]) on the relationship between glycemic control and cardiovascular fitness were explored. Method: Data were abstracted from a completed study that included 51 overweight or obese subjects with T2DM (n = 18), impaired glucose tolerance (n = 8), or normal glucose tolerance (n = 25). Relationships between glycemic control (HbA1c) and cardiovascular fitness (VO2 peak and VT) were determined using correlational analysis and multiple linear regression analyses. Results: A statistically significant relationship was observed between HbA1c and cardiovascular fitness. However, BMI and HOMA %S did not influence the relationship between glycemic control and cardiovascular fitness. Discussion: HbA1c contributes to VO2 peak and VT in obese and overweight subjects across glucose tolerance categories. Significant results were achieved despite the fact that there was a limited range of HbA1c based on the study inclusion criteria. This finding suggests that even a mild decrease in glycemic control can negatively influence cardiovascular fitness.