Reduction in severe hypoglycemia with long-term continuous subcutaneous insulin infusion in type I diabetes

OBJECTIVE - To compare the incidence of severe hypoglycemia in patients crossed over from multiple daily injections (MDIs) of insulin to continuous subcutaneous insulin infusion (CSII). RESEARCH DESIGN AND METHODS - From a population of 255 patients using CSII, all patients who met the following selection criteria were included in the present study. 1) a minimum of 12 months on intensive therapy with MDIs before switching to CSII, and 2) a minimum of 12 months on CSII after crossover. Glycemic control and adverse event rates for the 1-year MDI control period were compared with those for the CSII therapy period. RESULTS - The incidence of severe hypoglycemia during MDI therapy declined from 138 to 22 events per 100 patient-years during the Ist year of CSII (P < 0.0001) and remained significantly lower in years 2, 3, and 4 on CSII (26, 39, and 36, respectively). HbA(1c) levels did not change significantly between the MDI phase and any year on CSII. However, in the subgroup of patients who had pre-CSII HbA(1c) levels of greater than or equal to 8.0%, the change to CSII was associated with a significant reduction in HbA(1c) from baseline to year 1 (8.9 +/- 0.8 vs. 8.1 +/- 1.0%, P = 0.0004). The difference in diabetic ketoacidosis rates between the MDI year (14.6 events per 100 patient-years) and the CSII period (7.2 events per 100 patient-years) was not statistically significant. CONCLUSIONS - CSII therapy was associated with a marked and sustained reduction in the rate of severe hypoglycemia without adversely affecting the level of glycemic control attained during MDI therapy. The more reproducible and flexible insulin delivery afforded by CSII was considered to be the major factor contributing to the improvement in severe hypoglycemia rates.