OBJECTIVE: To assess the effect of mealtime amylin replacement with pramlintide on long-term glycemic and weight control in patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: In a 52-week, double-blind, placebo-controlled, multicenter study, 480 patients with type 1 diabetes were randomized to receive preprandial injections of placebo or 30 microg pramlintide q.i.d., in addition to existing insulin regimens. At week 20, pramlintide-treated patients were re-randomized to 30 or 60 microg pramlintide q.i.d. if decreases from baseline in HbA(1c) were <1% at week 13. Of the 342 patients who completed the 52-week study, 236 individuals ( approximately 70%) elected to participate in a 1-year open-label extension in which all patients received 30 or 60 microg pramlintide q.i.d. RESULTS: Treatment with pramlintide led to a mean reduction in HbA(1c) of 0.67% from baseline to week 13 that was significantly (P < 0.0001) greater than the placebo reduction (0.16%), and a significant placebo-corrected treatment difference was sustained through week 52 (P = 0.0071). The greater HbA(1c) reduction was associated with an average weight loss, rather than weight gain, and was not accompanied by an increased overall event rate of severe hypoglycemia. In the open-label extension, mean HbA(1c) levels decreased rapidly in patients receiving pramlintide for the first time and remained at reduced levels in patients who continued pramlintide treatment. The most common adverse events reported by the pramlintide group were mild nausea and anorexia, which both occurred during the initial weeks of treatment and dissipated over time. CONCLUSIONS: Mealtime pramlintide treatment as an adjunct to insulin improved long-term glycemic control without inducing weight gain or increasing the overall risk of severe hypoglycemia in patients with type 1 diabetes.