Differences in effects of insulin glargine or pioglitazone added to oral anti-diabetic therapy in patients with type 2 diabetes

BACKGROUND: While metformin is the first line treatment in type 2 diabetes, the best way to escalate therapy is not always clear, particularly whether to add one or two oral agents or to introduce insulin. METHODS: Thirty-six patients inadequately controlled on metformin and sulfonylurea/meglitinide were randomized to receive add-on therapy with insulin glargine or pioglitazone for 26 weeks. Insulin was up-titrated to achieve fasting plasma glucose 6.2%. beta-Cell function and insulin sensitivity were assessed by measuring insulin, proinsulin and adiponectin, and in a subgroup using a combined glucagon-stimulated C-peptide test and insulin tolerance test (GITT). Lipids and natriuretic peptides were measured at start and end of study. RESULTS: The reduction in HbA1c was slightly greater in the insulin glargine group and used as co-variate when analysing other variables. The effect on beta-cell function was more favourable with insulin glargine measured by proinsulin (42+/-48 to 19+/-16, p=0.01 vs. 36+/-26 to 27+/-16 p=0.04) while the improvement in insulin sensitivity measured by adiponectin (7.5+/-3.7 to 15+/-10, p