Is it safe for T1D patients to exercise after a meal?

Individuals with type 1 diabetes (T1D) may engage in postprandial exercise so long as they take necessary precautions (ie, prandial insulin reductions), suggests a study.

A team of investigators conducted a randomized controlled trial in eight adults with T1D (mean age 44 years, BMI 24 kg/m²), with four laboratory visits and 24-hour follow-up at home. Participants were randomized to undergo 30 minutes of rest (control), walking, or moderate-intensity (MI) or intermittent high-intensity (IHE) exercise performed 60 min after a standardized meal.

The primary outcome was change in blood glucose during exercise/control (acute), while secondary outcomes included the subacute (≤2 h after) and late glycaemic effects (≤24 h after).

Participants in the exercise group had lower PPG excursion than those in the control group, with a consistent decline in blood glucose in all T1D patients across modalities (control: mean decline, ‒45 mg/dL; MI: mean decline, ‒71 mg/dL; IHE: mean decline, ‒35 mg/dL; p<0.001).

“For this decline, clinical superiority was demonstrated separately for each exercise modality vs control,” the investigators said. The noninferiority of walking vs MI exercise was not demonstrated, as was the equivalence of IHE vs MI exercise. On the other hand, walking was not inferior to IHE exercise.

Hypoglycaemia did not occur in patients doing exercise, whereas blood glucose increased more an hour after exercise than after walking (p<0.001). More than half of the participants had hyperglycaemia following exercise, which required insulin correction. In addition, more nocturnal hypoglycaemic events occurred after exercise than after walking (p<0.05).

“[E]xercise lowered maximal PPG excursion and caused a consistent and clinically relevant blood glucose decline during exercise, while there was no hypoglycaemia during or shortly after exercise,” the investigators said. “However, there seem to be two remaining challenges: subacute postexercise hyperglycaemia and nocturnal hypoglycaemia.”