Don’t forget the negative effects of exercise
“It is well known that the three types of exercise can modulate glucose levels. This can be very useful when attempting to reduce excessively high glucose levels, and when encouraging people to engage in frequent, regular, and consistent physical activity and exercise for general cardiovascular pulmonary and musculoskeletal health,” Helena W. Rodbard, MD, an endocrinologist in private practice in Rockville, Md., said in an interview.
“However, it was not known what effects various types of exercise would have on time in range (70-180 mg/dL) and time below range (< 70 mg/dL) measured over a full 24-hour period in people with type 1 diabetes,” said Dr. Rodbard, who was not involved with the study.
“I was surprised to see that the effect of the three different types of exercise were so similar,” Dr. Rodbard noted. “There had been previous reports suggesting that the time course of glucose could be different for these three types of exercise.”
The current study confirms prior knowledge that exercise can help reduce blood glucose, and increase TIR, said Dr. Rodbard. The study shows that TIR increases by roughly 5-7 percentage points (about 1 hour per day) and reduces mean glucose by 9-13 mg/dL irrespective of the three types of exercise,” she said. “There was a suggestion that the risk of increasing hypoglycemia below 70 mg/dL was less likely for resistance exercise than for the interval or aerobic types of exercise,” she noted.
As for additional research, “This study did not address the various ways in which one can mitigate the potentially deleterious effects of exercise, specifically with reference to rates of hypoglycemia, even mild symptomatic biochemical hypoglycemia,” said Dr. Rodbard. “Since the actual amount of time below 70 mg/dL is usually so small (0.3%-0.7% of the 1,440 minutes in the day, or about 5-10 minutes per day on average), it is difficult to measure and there is considerable variability between different people,” she emphasized. “Finding optimal and robust ways to achieve consistency in the reduction of glucose, between days within subjects, and between subjects, will need further examination of various types of protocols for diet, exercise and insulin administration, and of various methods for education of the patient,” she said.
The study was supported in part by the Leona M. and Harry B. Helmsley Charitable Trust. Ms. Li and Dr. Rodbard had no financial conflicts to disclose. Dr. Rodbard serves on the editorial advisory board of Clinical Endocrinology News.