OBJECTIVE:--The purpose of this study was to determine the effect of cinnamon on glycemic control in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS--Using a prospective, double-blind, placebo-controlled design, 72 adolescent type 1 diabetic subjects were treated in an outpatient setting with cinnamon (1 g/day) or an equivalent-appearing placebo for 90 days. A1C, total daily insulin intake, and adverse events were recorded and compared between groups. RESULTS:--There were no significant differences in final A1C (8.8 vs. 8.7, P = 0.88), change in A1C (0.3 vs. 0.0, P = 0.13), total daily insulin intake, or number of hypoglycemic episodes between the cinnamon and placebo arms. CONCLUSIONS:--Cinnamon is not effective for improving glycemic control in adolescents with type 1 diabetes.