Structured exercise keeps blood sugar in check
Clinicians know that exercise can help patients with type 2 diabetes control blood glucose level, but exactly which type of regimen is best has been unclear until now.
Patients that perform aerobic exercise, resistance training, or some combination of both for more than 150 minutes each week reap the most benefits, data from a metaanalysis published this week in the Journal of the American Medical Association indicates.
Beatriz D. Schaan, MD, ScD, of the Hospital de Clinicas de Porto Alegre in Brazil, and colleagues reviewed data from 8,538 patients in 47 randomized controlled clinical trials from January 1980 to February 2011 to determine the effects of structured exercise training, physical activity advice and dietary cointerventions on hemoglobin A1c (HbA1c) levels in patients with type 2 diabetes.
They found that patients who participated solely in resistance training experienced a 0.57% drop in HbA1c levels, whereas those who participated in aerobic exercising programs reduced levels by 0.73% (P<0.001 for both). Combining both exercise modalities was associated with a 0.51% reduction in HbA1c levels compared with controls (P<0.001).
Patients who exercised for more than 150 minutes per week experienced significantly greater reductions in HBA1c levels vs. those who exercised fewer than 150 minutes per week — 89% vs. a 0.36% (P<0.001).
This has important implications for current guidelines, which state that patients should perform at least 150 minutes per week of moderate-intensity aerobic exercises and should perform resistance exercise three times per week.
“Although high-intensity exercise has been previously shown to have an association with HbA1c reduction, our findings did not demonstrate that more intensive exercise was associated with greater declines in HbA1c,” the researchers added.
Additional analyses revealed that interventions in which clinicians simply offered advice about physical activity without individualizing exercise plans or monitoring progress did not significantly reduce HbA1c levels. However, combining physical activity and dietary advice resulted in a 0.58% reduction in HbA1c compared with controls (P=0.007).
"This highlights the need for a combined recommendation of these lifestyle interventions," the researchers wrote.
Study limitations include unblinded data extraction and overall low study quality, the researchers acknowledged, both of which may have increased the risk of bias and contributed to heterogeneity in the analysis.
In an accompanying editorial Marco Pahor, MD, of the University of Florida, wrote that despite these limitations the available data “provide solid evidence for public policy makers to conisder structured exercise and physical activity programs worthy of insurance reimbursement to promote health, especially in high-risk populations.”
Pahor added that more rigorous trials are still needed to determine the efficacy of structured exercise programs across “a broad spectrum of important health outcomes,” as well as the cost effectiveness of such programs.