Long-term effect of weight loss on obstructive sleep apnea severity in obese patients with type 2 diabetes.

Study Objectives: To examine whether the initial benefit of weight loss on obstructive sleep apnea (OSA) severity at 1 year is maintained at 4 years. Design: Randomized controlled trial with follow-up at 1, 2, and 4 years. Setting: 4 Look AHEAD clinical centers. Participants: Two hundred sixty-four obese adults with type 2 diabetes and OSA. Interventions: Intensive lifestyle intervention with a behavioral weight loss program or diabetes support and education. Measurements: Change in apnea-hypopnea index on polysomnogram. Results: The intensive lifestyle intervention group's mean weight loss was 10.7 +/- 0.7 (standard error), 7.4 +/- 0.7, and 5.2 +/- 0.7 kg at 1, 2, and 4 years respectively, compared to a less than 1-kg weight loss for the control group at each time (P < 0.001). Apnea-hypopnea index difference between groups was 9.7 +/- 2.0, 8.0 +/- 2.0, and 7.7 +/- 2.3 events/h at 1, 2 and 4 years respectively (P < 0.001). Change in apnea-hypopnea index over time was related to the amount of weight loss (P < 0.0001) and intervention, independent of weight loss (P = 0.001). Remission of OSA at 4 years was 5 times more common with intensive lifestyle intervention (20.7%) than diabetes support and education (3.6%). Conclusions: Among obese adults with type 2 diabetes and OSA, intensive lifestyle intervention produced greater reductions in weight and apnea-hypopnea index over a 4 year period than did diabetes support and education. Beneficial effects of intensive lifestyle intervention on apnea-hypopnea index at 1 year persisted at 4 years, despite an almost 50% weight regain. Effect of intensive lifestyle intervention on apnea-hypopnea index was largely, but not entirely, due to weight loss.