Exercise plays a key role in any diabetes patient's effort to control blood sugar levels. Still, questions remain about the type, intensity and amount of exercise that is best for people with diabetes.
Both aerobic exercise (e.g., walking, running, swimming) and resistance exercise (e.g., weightlifting) can help patients with type 2 diabetes control their blood sugar, according to a recent study.
Researchers found that diabetes patients had larger drops in blood sugar the more exercise sessions they attended each week.
More specifically, it was aerobic exercise and combined exercise (aerobic plus resistance) that led to these reductions in blood sugar; not resistance training alone.
Research has shown that supervised exercise programs can improve blood sugar control in type 2 diabetes. However, it remains unclear what aspects of exercise are associated with reductions in HbA1c (a measure of blood sugar over time), explained the authors in background information to their study.
Daniel Umpierre, MSc, of Hospital de Clínicas de Porto Alegre in Brazil, and colleagues looked at past studies to better understand the link between the intensity and amount of exercise training and changes to HbA1c in patients with type 2 diabetes.
The HbA1c test shows how well patients have been controlling their blood sugar over the past 3 months. An HbA1c level of 5.6 percent or less is considered normal. Diabetes patients have an HbA1c of 6.5 percent or more. The goal for many diabetes patients is to keep their levels at or below 6.5 to 7 percent.
They found that each additional session of aerobic exercise per week may reduce HbA1c by 0.39 percent.
While the amount of resistance exercise alone did not seem to affect levels of HbA1c, the amount of resistance exercise in combined training with aerobic exercise was associated with changes in HbA1c.
According to the authors, these finding highlighted the importance of exercise volume (frequency of exercise sessions) in improving blood sugar.
"In this context, the present study demonstrates that the frequency of exercise is the specific factor more likely to underlie the beneficial effects of aerobic training, meaning that the repetition of exercise sessions may be more important than longer or more intense sessions," the authors said.
In other words, more exercise sessions per week may do more for blood sugar control than longer, more difficult sessions.
Results from a previous study by Dr. Umpierre and fellow researchers - which were included in the current study - showed that exercise sessions lasting longer than 150 minutes (two and a half hours) were associated with drops in HbA1c of 0.89 percent. This finding "highlighted an important role of the exercise volume in the exercise-induced [blood sugar] improvements," the researchers said.
The researchers concluded that exercise frequency in aerobic training and the frequency of sessions of resistance exercise in combined training are associated with reductions in HbA1c.
Overall, the study showed that supervised exercise training may reduce levels of HbA1c by about 0.6 percent, which is similar to the effect of adding non-insulin diabetes drugs to metformin therapy - the most commonly used diabetes drug.
This finding suggests that exercise - the cheaper and safer option - may help diabetes patients as much as certain drugs.
For their study, Dr. Umpierre and colleagues reviewed 26 previous studies, which included a total of 2,253 patients. The research was partially supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior among others.
Co-author Dr. Jorge Pinto Ribeiro of Universidade Federal do Rio Grande do Sul reported having received lecturing fees from AstraZeneca and Servier as well as grant support from Boehringer Ingelheim, Bristol-Myers Squibb, Merck Sharp & Dohme, Servier and Takeda. The other authors reported no potential conflicts of interest. The study was published November 16 in Diabetologia.