Blood pressure response to melatonin in type 1 diabetes

Diminished decline of blood pressure at night has been associated with increased risk of cardiovascular disease. Exogenous melatonin given to healthy normotensive adults reduces blood pressure. We hypothesized that melatonin increases the decline of blood pressure during sleep in normotensive adolescents with type 1 diabetes.

Eleven normotensive normoalbuminuric patients with type 1 diabetes of 7.0 +/- 3.5 yr duration and 10 healthy controls aged 14-18 yr participated in a randomized placebo-controlled double-blind crossover study of 5 mg melatonin for 1 wk, with a 1-wk washout. Blood pressure was measured every 20 min for 24 h by an ambulatory device on the day before and on the last day of each treatment. Sleep measures were recorded by a diary and a wrist activity meter. Blood pressure measures were grouped by 24 h, sleep, and wake periods. Statistical analysis used sleep duration, number of awakenings, and treatment sequence as covariates for the blood pressure comparisons by treatment.

In the patients with type 1 diabetes, the decline in diastolic blood pressure during sleep was significantly greater on melatonin (17.8 +/- 4.4 mmHg) than on placebo (16.0 +/- 3.0 mmHg, p < 0.01). No significant drug effect was present in the controls. No significant side effects were noted.

Melatonin amplifies the nocturnal decline in diastolic blood pressure in patients with type 1 diabetes. We propose that dose-response studies of short- and long-acting preparations of melatonin be conducted and that melatonin be considered in trials of prevention of hypertension in type 1 diabetes.