Insulin is a hormone that controls the levels of glucose, a key source of energy, in our blood via its effects on the liver, muscle, and fat cells. How insulin affects the heart is not very clear, animal studies suggest that insulin protects the heart from stresses, whereas clinical studies suggest a link between high levels of insulin in the blood and heart failure.

The team, led by Issei Komuro, has generated data in mice indicating that while persistent high blood pressure induces liver cell resistance to insulin, it enhances insulin signaling in the heart. This excessive chronic insulin signaling exacerbated heart failure caused by high blood pressure. Importantly, although treating type 1 diabetic mice, which produce no insulin, with insulin stabilized their levels of glucose in the blood, it increased heart failure.

Together, these data lead the authors to suggest that insulin treatment could be harmful in the setting of chronic high blood pressure and that maintaining insulin signaling at normal levels is crucial for treating heart failure.

The research appears in the Journal of Clinical Investigation.