Taking melatonin supplements helps improve blood vessel health in heart failure patients who don't have diabetes, but it doesn't seem to help those who do have diabetes. This suggests that a person's blood sugar levels might change how well melatonin works to protect the heart and blood vessels.

Our current analysis shows that the evidence we have reviewed leans toward finding no clear benefit from melatonin for blood vessel function in heart failure patients, and it does not support the idea that diabetes changes how melatonin works. We analyzed one assertion and found that zero studies support the claim, while thirty-nine studies refute it [1]. What we have found so far is that the available research does not back up the idea that melatonin supplements improve blood vessel health in heart failure patients who do not have diabetes. Heart failure is a condition where the heart does not pump blood as well as it should. Blood vessel function refers to how well the tubes that carry blood can expand and relax to move blood smoothly. The evidence we have reviewed suggests that melatonin does not appear to help these patients. We also found no proof that having diabetes changes how melatonin affects the heart and blood vessels. The thirty-nine studies we looked at do not show a meaningful link between melatonin use and better blood vessel health in either group. The evidence we have reviewed leans toward the conclusion that melatonin does not improve blood vessel function in heart failure patients, regardless of diabetes status. Our current analysis is based on the studies available right now, and this view may change as more research becomes available. We do not have enough evidence to say that melatonin works for this specific group, and we cannot confirm that blood sugar levels change how melatonin protects the heart. If you have heart failure and are considering melatonin for sleep or other reasons, talk to your doctor first. They can help you weigh the known effects of melatonin against your specific heart and blood sugar health. For now, the studies we have reviewed do not show that melatonin will improve how your blood vessels work.