The Resistance Exercise in Already Active Diabetic Individuals (READI) Randomized Clinical Trial

Context Resistance exercise training (strength training) and aerobic exercise training are both recommended for people with type 1 diabetes, but it is unknown whether adding resistance exercise provides incremental benefits in people with this condition who already perform aerobic exercise regularly. Objective This work aimed to evaluate the incremental effect of resistance training on glycated hemoglobin A(1c) (HbA(1c)), fitness, body composition, and cardiometabolic risk factors in aerobically active people with type 1 diabetes. Methods The Resistance Exercise in Already-active Diabetic Individuals (READI) trial (NCT00410436) was a 4-center, randomized, parallel-group trial. After a 5-week run-in period with diabetes management optimization, 131 aerobically active individuals with type 1 diabetes were randomly assigned to resistance exercise (n = 71, intervention-INT) or control (n = 60, CON) for 22 additional weeks. Both groups maintained their aerobic activities and were provided dietary counseling throughout. Exercise training was 3 times per week at community-based facilities. The primary outcome was HbA(1c), and secondary outcomes included fitness (peak oxygen consumption, muscle strength), body composition (anthropometrics, dual-energy x-ray absorptiometry, computed tomography), and cardiometabolic risk markers (lipids, apolipoproteins). Assessors were blinded to group allocation. Results There were no significant differences in HbA(1c) change between INT and CON. Declines in HbA(1c) (INT: 7.75 +/- 0.10% [61.2 +/- 1.1 mmol/mol] to 7.55 +/- 0.10% [59 +/- 1.1 mmol/mol]; CON: 7.70 +/- 0.11% [60.7 +/- 1.2 mmol/mol] to 7.57 +/- 0.11% [59.6 +/- 1.3 mmol/mol]; intergroup difference in change -0.07 [95% CI, -0.31 to 0.18]). Waist circumference decreased more in INT than CON after 6 months (P = .02). Muscular strength increased more in INT than in CON (P < .001). There were no intergroup differences in hypoglycemia or any other variables. Conclusion Adding resistance training did not affect glycemia, but it increased strength and reduced waist circumference, in aerobically active individuals with type 1 diabetes.