The study group consisted of 96 patients who had used a medication for type 2 diabetes; of them, 33 had undergone gastric sleeve surgery and 63 bypass surgery. Both surgical methods resulted in a similar weight loss among the patients. In follow-up 39 out of 88 patients were able to manage without antidiabetic drugs two years after surgery. The costs of antidiabetic drugs two years after surgery were 79% lower than before the operation. Weight reduction surgery decreases the need for antidiabetic drugs. The greatest cost-efficiency is achieved by targeting weight-loss operations to patients using insulin therapy.