10 Jun Diabetes: Adding Insulin To Metformin May Increase Cardiovascular Risk
MedicalResearch.com Interview with:
Christianne L. Roumie, MD MPH
Associate Professor Internal Medicine and Pediatrics
Institute for Medicine and Public Health
Staff Physician VA Tennessee Valley Healthcare System
Nashville TN 37212
MedicalResearch: What are the main findings of the study?
Dr. Roumie: This retrospective cohort study compared time to acute myocardial infarction (AMI), stroke, or death among Veterans with diabetes that were initially treated with metformin, and subsequently added either insulin or sulfonylurea. Among 178,341 Veterans on metformin monotherapy, 2,948 and 39,990 added insulin or sulfonylurea, respectively. Patients were about 60 years old, about 35% had history of heart disease or stroke, had been on metformin for an average of 14 months and their hemoglobin A1c was 8.1% at the time of addition of the second medication. Compared to those who added a sulfonylurea, those who added insulin to metformin had a 30% higher risk of the combined outcome of heart attack, stroke, and all-cause mortality. Although new heart attacks and strokes occurred at similar rates in both groups, mortality was higher in patients who added insulin.
MedicalResearch: Were any of the findings unexpected?
Dr. Roumie: Insulin is a very good medication in reaching blood sugar control, and because of that prior large studies have found that it reduces the risk of developing diabetic kidney or eye disease. This study and others however have shown that tighter glucose control doesn’t necessarily have any benefit for heart disease.
MedicalResearch: What should clinicians and patients take away from your report?
Dr. Roumie: Intensification of metformin with insulin among those who could add a sulfonylurea (HbA1c <10%) offers no advantage on risk of cardiovascular events and is associated with some risk.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. Roumie: At present, the underlying mechanisms which may explain the increased risk of death found in the study remain unknown. We have a number of studies planned to examine possible mechanisms. We are investigating type 2 diabetes outcomes associated with blood glucose swings and with episodes of hypoglycemia (low blood sugar) tied with both insulin and sulfonylurea use. However, I think a pragmatic trial evaluating these diabetic regimens and focusing on patient outcomes, not only HbA1c is needed.