Background Thiazolidinediones (rosiglitazone, pioglitazone) are oral insulin-sensitizing medications used in type 2 diabetes mellitus that reduce glucose with minimal risk of hypoglycemia and potential benefits on atherosclerosis. However, thiazolidinediones can cause fluid retention thereby increasing the risk of heart failure-a common complication of type 2 diabetes mellitus. Methods and Results Data were analyzed from the Diabetes Collaborative Registry, a US outpatient registry of patients with type 2 diabetes mellitus that currently encompasses 203 cardiology, endocrinology, and primary care practices and 3074 providers. Among 424 061 US adults enrolled in Diabetes Collaborative Registry who had type 2 diabetes mellitus and were taking ≥1 glucose-lowering medication, 35 018 patients (8.3%) were on a thiazolidinedione, which has remained stable over time. Patients on thiazolidinediones tended to be old (mean age, 69.2±10.7 years), 61.9% had coronary disease, and 17.2% had class 3 obesity. In total, 40.3% of patients on a thiazolidinedione had either a clinical diagnosis of heart failure (23.7%), had an ejection fraction of <40% (7.7%), or were on a loop diuretic (29.9%). Conclusions Although thiazolidinediones lost significant market share after 2007 when concerns arose regarding their safety, thiazolidinediones are still commonly used. At least a quarter, and up to two-fifths, of patients currently treated with thiazolidinediones have some evidence of heart failure and therefore should not be candidates for this therapy. Accordingly, heart failure concerns with thiazolidinediones may be under-recognized.
Keywords: atherosclerosis; diabetes mellitus; heart failure; insulin; thiazolidinediones.