OBJECTIVES: The objectives were to assess whether rapid transitioning in newly diagnosed type II diabetics from diet and exercise to insulin results in better blood glucose control as measured by HbA1C and reduced diabetes-related complications. METHOD: We used longitudinal data from IMS Mediplus-Germany for newly diagnosed type II diabetics between June 1993 and May 2001 with at least two HbA1C readings. Patients with complications at baseline were excluded. Treatment was categorized as diet and exercise, sulfonylureas, antihyperglycemic drug combinations, insulin or insulin plus another agent. Modifications to treatment were tracked and rapid use of insulin was either initial insulin use or immediate change from diet and exercise to insulin. Area under the curve (AUC) for HbA1C was calculated and divided by the duration of time in the data. A regression model explained AUC as a function of rapid transitioning to insulin. A Cox model assessed the relationship between the time to first complication and AUC, rapid transition to insulin and the number of modifications. RESULTS: A total of 3137 patients satisfied all study entry criteria; 1230 patients were initiated on diet and exercise, 1756 on oral agents, and 151 on insulin. Demographics were comparable. Of patients initiated on diet and exercise 66 switched to insulin in 2.4 months. In the linear regression model explaining AUC (R2 = 0.185), rapid transition to insulin was significant (-0.19, p = 0.04) indicating that insulin sooner improves blood glucose control. Of the 3137 patients, 954 encountered complications. Time to first complication was negatively related to AUC (-0.04, p <0.01) and rapid use of insulin (-0.45, p <0.01) with hazard ratios of 0.962 and 0.637 and positively related to the number of modifications (0.08, p <0.01) with a hazard ratio of 1.083. CONCLUSIONS: Initial or immediate transition to insulin results in better blood glucose control that reduces the onset of diabetes-related complications.