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Exercise improves disease severity biomarkers in type 1 diabetes

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January 4, 2018

Results from a systematic review and meta-analysis show that patients with type 1 diabetes who exercised experienced improvement in several different markers of disease severity.

Neil Smart
Neil Smart

“This pooled data analysis revealed that relatively few exercise training studies in people with type 1 diabetes have been published in comparison to those with type 2 diabetes,” Neil A. Smart, MD, professor of exercise and sports science at the school of science and technology at the University of New England, Armidale, Australia, told Endocrine Today.Moreover, the existing type 1 studies vary greatly in terms of the exercise programming, age of participants (adults vs. children) and confounders within study designs.”

The researchers used multiple databases, including MEDLINE, the Cochrane Controlled Trials Registry, SPORTDiscus, the Science Citation Index and CINAHL to identify clinical trials of exercise in patients with type 1 diabetes.

Adults with type 1 diabetes demonstrated significant improvements in BMI (mean difference, –0.39 kg/m2; 95% CI, –0.75 to –0.02) and body mass (mean difference, –2.20 kg; 95% CI, –3.79 to –0.61), as well as peak oxygen intake (mean difference, 4.08 mL/kg/min; 95% CI, 2.18-5.98) and LDL cholesterol (mean difference, –0.21 mmol/L; 95% CI, –0.33 to –0.08), the researchers reported.

Children showed significant improvements in other areas, Smart and colleagues wrote, including insulin dose (mean difference, –0.23; IU/kg; 95% CI, –0.37 to 0.09), waist circumference (mean difference, –5.4 cm; 95% CI, –8.45 to –2.35), triglycerides (mean difference, –0.21 mmol/L; 95% CI, –0.42 to –0.01) and LDL cholesterol (mean difference, –0.31 mmol/L; 95% CI, –0.55 to –0.06).

Smart and colleagues reported no changes in resting heart rate, resting systolic blood pressure, HDL, HbA1c or fasting blood glucose in either children or adults.

“Exercise training appears to confer some benefits in terms of medication use and cardiovascular disease risk factors, but does not exert much effect on glucose metabolism,” Smart said. “As type 1 diabetes is not necessarily a disease caused by an ‘excess lifestyle,’ future work might focus on low-volume, vigorous to high-intensity exercise interventions that optimize GLUT 4 transporter influence. Future work might also benefit from researchers within this field coming together to standardize study design and reporting with the goal of minimizing variation in the parameters.” . – by Andy Polhamus

Disclosures: The authors report no relevant financial disclosures.

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Exercise was associated with improvement in disease severity biomarkers in adults and children with type 1 diabetes

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Sheri Colberg

Due to the complexities of managing glycemia in individuals with type 1 diabetes during exercise, the limited studies that have been done in this area are by nature heterogeneous, reporting on different types of activities, metabolic outcomes, and even populations (adults vs. children with type 1 diabetes). This systematic review and meta-analysis by Jewiss and colleagues clearly ran into some of these same issues when trying to pool data from studies with different conditions. Nonetheless, the conclusions that they were able to reach back prior assertions that individuals with type 1 diabetes — regardless of their age — can gain many health benefits from participating in physical activities that are afforded to those without diabetes.

The most important finding by these authors, in my opinion as an exercise physiologist specializing in diabetes and health management, is that physical activity lowers total insulin requirements, suggesting that insulin sensitivity is improved by regular exercise in both adults and children with type 1 diabetes. Being able to take lower doses of insulin may prevent severe hypoglycemia and reduce health risks associated with a hyperinsulinemic state. 

Another notable finding was a reduction in waist circumference with exercise. Given that waist size is an indicator of cardiovascular risk and that individuals with diabetes already have a higher risk for cardiovascular disease, lowering this risk is of paramount importance in preventing premature mortality and morbidity.

Finally, it is not surprising that no uniform improvements in overall blood glucose management (HbA1c) were evidence in pooled data. Some types of physical activity can raise blood glucose (eg, intense training) rather than lower it, and keeping blood glucose in more normal ranges with physical activity requires a sophisticated balancing act with adjustments in insulin dosing, food intake and more. The findings of this review and meta-analysis, though, should give more incentives to health care providers to recommend physical activity as a part of health management for all individuals with type 1 diabetes.

Sheri R. Colberg, PhD, FACSM

Professor Emerita of Exercise Science

Old Dominion University


Disclosure: Colberg reports no relevant financial disclosures.