This is the first report of the long-term effect of the ileogastrostomy on diabetes mellitus and sleep apnea. The ileogastrostomy was associated with rapid improvement or normalization of diabetes mellitus, similar to the biliopancreatic diversion and the Roux-en-Y gastric bypass, but faster than other bariatric operations. Improvement in sleep apnea was slower and was related to weight loss, similar to other bariatric operations.