CHICAGO – Insulin glargine showed no effects on left ventricular mass or function during 3 years of follow-up in dysglycemic patients at high cardiovascular risk in the ORIGIN echocardiographic substudy.
This echocardiographic study of the ORIGIN (Outcome Reduction With an Initial Glargine Intervention) trial, the largest reported study of the effects of exogenous insulin on left ventricular mass and LV systolic and diastolic function, provides reassuring new evidence that insulin glargine is safe from a cardiac standpoint, Dr. Michelle Haroun said at the American Heart Association scientific sessions.
“The key here is that we didn’t see any signal whatsoever to suggest that insulin is putting patients at increased risk. We think that this finding is important. While you need to follow patients for a very long time to detect changes in clinical heart failure outcomes, we think we’d be able to detect subtle changes in endpoints like LV mass over a 3-year period if insulin was of harm to patients,” said Dr. Haroun of the Population Health Research Institute at McMaster University in Hamilton, Ont.
ORIGIN-ECHO involved 564 dysglycemic patients at high cardiovascular risk who were randomized to insulin glargine (Lantus) or standard therapy. All had echocardiograms at baseline and after 3 years of therapy. Participants had to have impaired fasting blood glucose, impaired glucose tolerance, or early type 2 diabetes managed with no more than one oral antiglycemic drug at baseline. This was a group at high cardiovascular risk: 32% had a prior MI, 84% had a history of hypertension, obesity was common, and the average age was 64. However, none of the participants had heart failure at baseline.
The study was undertaken because some of the medications used to treat hyperglycemia are associated with increased risk of heart failure. Regulatory agencies, physicians, and patients want to see evidence of cardiovascular safety, and until ORIGIN-ECHO, the effects of exogenous insulin on LV mass and function hadn’t been well studied.
Baseline LV mass and function values were within normal range and did not change significantly over 3 years of follow-up in either treatment arm. For example, left ventricular mass/height averaged 116 g/m at baseline and 115 g/m after 3 years on insulin glargine, and was comparable at 113 and 114 g/m, respectively, with standard therapy. This was an unexpected finding, according to Dr. Haroun.
“We thought patients with diabetes on standard therapy were going to develop left ventricular hypertrophy over a 3-year follow-up period, and they didn’t. That came as a bit of a surprise to us. We expected to see a lower rate of LVH in the patients on insulin glargine. This patient population was relatively early in their course of diabetes, and we believe our findings suggest that adequate management of cardiovascular risk factors – especially hypertension– and the use of cardioprotective drugs in this population may prevent or delay abnormalities in LV structure and function,” she said.
The primary outcomes of the full ORIGIN study involving more than 12,000 patients have previously been published (N. Engl. J. Med. 2012; 367:319-28). ORIGIN was sponsored by Sanofi. Dr. Haroun reported having no financial conflicts.