Can good aerobic fitness mean good glycemic control?

This study examined whether having a good level of cardiorespiratory fitness is related to good blood sugar level control. 

Cardiorespiratory (aerobic) fitness is the body’s ability to pump blood and deliver oxygen to muscles during exercise. It is thought that having a good level of aerobic fitness protects against the development of type 2 diabetes (T2D). It is also thought that people who have a high level of this fitness have good glycemic (blood glucose level) control.

313 people took part in this study.  137 patients had normal glucose tolerance, 85 had impaired glucose tolerance and 91 had T2D.

Patients underwent a fitness test to find out their VO2 max, a measure of cardiorespiratory fitness. Vo2 max measures the level at which the body functions most effectively during exercise. HbA1c (average blood glucose levels over the past 3 months), fasting blood glucose (glucose levels following a period without food or drink), and 2-hour glucose tolerance (how long it takes for blood glucose levels to return to normal after a glucose drink is taken) were measured.

Overall, patients with a high VO2 max (high level of fitness) had good glycemic control. Those with normal glucose tolerance had an average VO2 max of 37.0 ml/kg/min and an HbA1c of 5.54%. Patients with impaired glucose tolerance had an average VO2 max of 25.1 ml/kg/min and an HbA1c of 5.69%. Those with T2D had an average VO2 max of 26.2 ml/kg/min and an HbA1c of 6.59%.

Lower VO2 max was associated with higher fasting blood glucose levels and higher 2-hour glucose tolerance.

VO2 max was also found to be related to insulin sensitivity (the sensitivity of the body to insulin, the hormone needed to break down the glucose taken in from food). Those without diabetes and sensitive to insulin had a high VO2 max, and those with T2D had a low VO2 max and were the least sensitive to insulin.  

This study found that having a high level of aerobic fitness can be related to good glycemic control. 

Many of the patients with T2D in this study were treated with glucose lowering medications. They stopped taking these medicines 5 days prior to the study, so some of the results may be related to the body’s withdrawal from these medicines. 

Discuss with your physican lifestyle changes such as increasing fitness levels, as this could help your blood sugar control.