Benefits of exercise shown to depend on duration, not exercise type
For many diabetes patients, the lack of physical activity is high and most patients do not do the recommended 150 min of moderate-intensity physical activity or 75 min vigorous intensity activity per week by the World Health Organization (WHO).
This new study was a systematic review to evaluate the role of physical activity and attempt to define potential factors responsible for stronger impacts on fasting blood glucose and HbA1c. To do the systematic review, the literature search was restricted to articles published in English up to December 2015 in the PubMed database. The search terms used were “physical activity,” “physical exercise,” “type 1 diabetes,” “type 2 diabetes,“ pre-diabetes,” or “randomized control trials.”
To select the studies, randomized controlled trials of physical activity interventions that reported a change in fasting blood glucose or HbA1c were included. The studies could have control groups with no physical activity or another group with lower intensity as the comparison. Studies with more than 1-week follow-up were included as well since HbA1c requires a longer time frame to observe changes. The studies that included nutritional changes were excluded to limit bias.
In total there were 4,360 references identified and 304 met eligibility criteria based on title and abstract. After evaluating the full texts, 179 of those publications were excluded. In 105 studies that had data on fasting blood glucose, the overall statistically significant decrease in fasting blood glucose was observed with increasing duration of physical activity, each additional 100 min per week of physical activity was associated with a mean average decrease of -2.75 mg/dl of fasting glucose. In 56 studies, the associate on physical activity and fasting blood glucose was significantly higher in people with type 2 diabetes; an increase of 100 min in physical activity per week had a decrease of -4.71 mg/dl.
In 76 studies that reported HbA1c, most reported data longer than 12 weeks with a mean duration of 21 weeks. In these studies, each additional 100 min of physical activity per week had a mean decrease of -0.14% in HbA1c. These findings were greater in the studies of people with type 2 diabetes prediabetes as compared to those without diabetes. The level and strength of association between duration of physical activity and decrease in FBG or HbA1c was independent of the type or intensity of physical activity.
Many health organizations already have physical activity as a key preventative measure to reduce fasting blood glucose and HbA1c. This meta-analysis confirmed that it is beneficial to have increased physical activity to reduce levels of fasting blood glucose and HbA1c.
Some limitations in this study were the heterogeneity of the studies; possibility of publication bias in the evaluation of HbA1c, and this study was only an evaluation of recent physical activity on fasting blood glucose and HbA1c, not long-term impact.
Overall, increasing physical activity can reduce fasting blood glucose and HbA1c levels. The study also found that the benefits of physical activity depend on the duration of exercise and not the type of physical activity, so every exercise can be individualized.
- An increase of 100 min in physical activity per week was associated with an average change of -2.75 mg/dl in fasting glucose.
- An increase of 100 min in physical activity per week was associated with an average change of -0.145 of HbA1c.
- Lack of physical activity is seen in 60% of people with prediabetes and diabetes.
Boniol M, Dragomir M, Autier P, et al. Physical activity and change in fasting glucose and HbA1c: a quantitative meta-analysis of randomized trials. Acta DIabetol (2017) 54:983. https://doi.org/10.1007/s00592-017-1037-3.
Jessica Quach Doctor of Pharmacy Candidate 2018, GA-PCOM School of Pharmacy