Exercise Modes and their Association with Hypoglycaemia Episodes in Adults with Type 1 Diabetes Mellitus: A Systematic Review

Objective: Type 1 diabetes mellitus rates are rising worldwide. Health benefits of physical exercise in this condition are many, but more than 60% do not participate, mainly from fear of hypoglycaemia. This systematic review explores effects of physical exercise modes on blood glucose levels in adults for hypoglycaemia prevention. Research Design and Methods: Predefined inclusion criteria were randomised or non-randomized crossover trials of healthy non-obese adults with type 1 diabetes mellitus. Exercise interventions used standardised protocols of intensity and timing. Outcomes included hypoglycaemia during or after exercise, and acute glycaemic control. Medline, CINAHL, AMED, SportDiscus, CENTRAL (1990–11/01/2018), Embase, (1988-09/04/2018) were searched using keywords and MeSH terms. Inclusions, data-extraction, and quality assessment using CASP checklists, were by one researcher and checked by a second. Meta-analysis used Revman (version 5.3) where four or more outcomes were reported. PROSPERO registration CRD42018068358. Results: From 5459 citations, we included 15 small crossover studies (3 non-randomised), 13 assessing aerobic (intermittent high-intensity exercise (IHE) versus continuous, or continuous versus rest) and 2 assessing resistance exercise versus rest. Study quality was good, and all outcome measures reported. Thirteen gave hypoglycaemia results, of which 5 had no episodes. Meta-analysis of hypoglycaemia during or after IHE compared to continuous exercise showed no significant differences (N=5,OR=0.68(95%CI0.16-2.86),I2=56%). For blood glucose there was little difference between groups at any time point. Conclusion: IHE may be safer than continuous exercise because of lesser decline in blood glucose, but more research needs to demonstrate if this would be reflected in hypoglycaemic episode rates.