Long-term efficacy of triple oral therapy for type 2 diabetes mellitus

To report the status of 35 patients with type 2 diabetes mellitus approximately 3 years after the initiation of triple oral antidiabetic therapy--with a sulfonylurea, metformin, and a thiazolidinedione.

Study patients were assessed for the need for the addition of insulin, and follow-up clinical and laboratory findings were analyzed.

At a mean follow-up of 37 months (range, 18 to 45), 26 (74%) of 35 patients (group A) had well-controlled blood glucose levels on triple oral therapy, with a mean glycated hemoglobin (HbA1c) value of 6.9 +/- 0.3% (upper limit of normal, 6.5%). In the nine other patients (group B), triple oral therapy failed and the use of insulin was necessary after a mean duration of 30 months (range, 18 to 42); the mean HbA1c in these patients was 8.8 +/- 0.5%. Both group A and B gained similar amounts of weight during the study period (14.2 +/- 2.1 lb versus 11.6 +/- 3.8 lb, respectively; P = 0.54). A search for potential predictors of success or failure revealed that both groups had similar baseline characteristics, including age, duration of diabetes, weight, body mass index, HbA1c, and baseline stimulated C-peptide levels, and none of these factors demonstrated a significant correlation with the response to therapy. The only difference found between the two groups was a significant increase in the stimulated C-peptide levels (from 3.6 +/- 0.9 ng/mL to 5.2 +/- 1.1 ng/mL; P = 0.002) during follow-up in the group that had good glycemic control with triple oral therapy, in comparison with a nonsignificant increase (from 3.7 +/- 0.8 ng/mL to 4.2 +/- 0.4 ng/mL; P = 0.46) in the group that failed to maintain glycemic control on triple oral therapy.

Triple oral antidiabetic therapy is an effective long-term treatment for a substantial proportion of patients with type 2 diabetes who initially achieve glycemic control with triple oral therapy, particularly those in whom production of endogenous insulin is increased when a thiazolidinedione is added.