(HealthDay News) – The effects of exercise on glycemic control in patients with type 2 diabetes mellitus (T2DM) are dependent on glucose levels prior to training, according to a research letter published online July 1 in JAMA Internal Medicine.

Thomas P.J. Solomon, PhD, of Rigshospitalet in Copenhagen, Denmark, and colleagues examined the association between pretraining glycemic state and changes in glycemic control following 12–16 weeks of aerobic exercise training in 105 individuals with impaired glucose tolerance or T2DM.

The researchers found significant improvements following exercise training, including reduction in body weight and whole-body adiposity, increased maximal oxygen uptake, and reduced fasting plasma glucose levels and two-hour oral glucose tolerance test (OGTT) levels. Fasting plasma glucose level before training did not affect exercise-induced changes in glycemic control. For the OGTT, individuals with a pretraining level of <13.1mmol/L had significantly greater exercise-induced decreases in the two-hour glucose level than those with a higher pretraining level. The same association was observed for hemoglobin A1c (HbA1c), with significantly greater exercise-induced decreases in HbA1c level seen in those with a pretraining level <6.2% than in those with a higher pretraining level.

“Because chronic hyperglycemia (>6.2% HbA1c level; >13.1-mmol/L glucose level) potentially predicts a poor therapeutic effect of aerobic exercise on glycemic control and fitness, using exercise to treat patients with poorly controlled T2DM may have limited chances of a successful outcome,” the authors write.

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