OBJECTIVE: To assess the effects of adjunctive treatment with pramlintide, an analog of the beta-cell hormone amylin, on 24-h glucose fluctuations and postprandial glucose, glucagon, and triglyceride excursions in patients with type 1 diabetes intensively treated with continuous subcutaneous insulin infusion (CSII). RESEARCH DESIGN AND METHODS: In this study, 18 patients (16 of whom could be evaluated) with type 1 diabetes (age 44 +/- 11 years, HbA(1c) 8.2 +/- 1.3% [mean +/- SD]) were given mealtime injections of 30 micro g pramlintide t.i.d. for 4 weeks in addition to their preexisting CSII regimen (16 lispro, 2 regular insulin). Mealtime insulin boluses were reduced by a minimum of 10% during the first 3 days, and re-adjusted thereafter based on clinical judgment. At weeks 0 (baseline), 4 (on treatment), and 6 (2 weeks off treatment), 24-h interstitial glucose concentrations were measured using a continuous glucose monitoring system (CGMS), and postprandial plasma glucose, glucagon, and triglyceride concentrations were measured in response to a standardized test meal. RESULTS: At baseline, patients had excessive 24-h glucose fluctuations, with 59% of the CGMS measurements >140 mg/dl, 13% <80 mg/dl, and only 28% in the euglycemic range (80-140 mg/dl). After 4 weeks on pramlintide, measurements in the hyperglycemic range declined to 48% and measurements within the euglycemic range increased to 37%. This shift from the hyperglycemic to the euglycemic range occurred with a concomitant 17% reduction in mealtime insulin dosages and without relevant increases in measurements below the euglycemic range (15%) or any severe hypoglycemic events. After 4 weeks on pramlintide, postprandial glucose, glucagon, and triglyceride excursions were reduced by approximately 86, approximately 87, and approximately 72%, respectively (incremental areas under the curve, all P < 0.05 vs. baseline). At week 6 (off treatment), the 24-h glucose profile and postprandial glucose, glucagon, and triglyceride excursions approached pretreatment values. CONCLUSIONS: In this study, the addition of pramlintide to insulin therapy reduced excessive 24-h glucose fluctuations as well as postprandial glucose, glucagon, and triglyceride excursions in patients with type 1 diabetes intensively treated with insulin pumps.