Is too much insulin bad for the heart?

WASHINGTON - Using insulin to treat diabetes could be harmful if the patient has chronic high blood pressure (BP), says the latest research.

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 stress, whereas clinical studies suggest a link between high levels of insulin in the blood and heart failure.

The team, led by Issei Komuro from Chiba University Graduate School of Medicine in Japan has generated data in mice indicating that while persistent high BP induces liver cell resistance to insulin, it enhances insulin signalling in the heart.

This excessive chronic insulin signalling aggravated heart failure caused by high BP. Importantly, although treating type I diabetic mice - which produce no insulin - with insulin stabilised their levels of glucose in the blood, it increased heart failure, says a China University release.

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

The research was published in the Journal of Clinical Investigation.