Tomris Erbas | Search PubMed

PubMed2005

Melatonin levels decrease in type 2 diabetic patients with cardiac autonomic neuropathy.

The present study has been designed to determine melatonin levels in type 2 diabetic patients and test the relationship between the autonomic nervous system and melatonin dynamics. Thirty-six type 2 diabetic patients and 13 age-matched healthy subjects were recruited for the study. Circadian rhythm of melatonin secretion was assessed by measuring serum melatonin concentrations between 02:00-04:00 and 16:00-18:00 hr. Melatonin dynamics were re-evaluated with respect to autonomic nervous system in diabetic patients with autonomic neuropathy who were diagnosed by the cardiovascular reflex tests, heart rate variability (HRV), and 24-hr blood pressure monitoring. Nocturnal melatonin levels and the nocturnal melatonin surge were low in the diabetic group (P = 0.027 and 0.008 respectively). Patients with autonomic neuropathy revealed decreased melatonin levels both at night and during day when compared with healthy controls (P < 0.001 and 0.004 respectively) while the melatonin dynamics were similar to controls in patients without autonomic neuropathy. Nocturnal melatonin level was positively correlated with nocturnal high and low frequency components of HRV (P = 0.005 and 0.011 respectively) and systolic and diastolic blood pressures at night (P = 0.002 and 0.004 respectively) in patients with autonomic neuropathy. We found a negative correlation between nocturnal melatonin levels and the degree of systolic blood pressure decrease at night (r = -0.478, P = 0.045). As a conclusion this study has shown that circadian rhythm of melatonin secretion is blunted in type 2 diabetic patients and there is a complex relationship between various components of autonomic nervous system and melatonin secretion at night. Among the patients with autonomic neuropathy those with more preserved HRV and the systolic nondippers (<10% reduction in blood pressure during the night relative to daytime values) have more pronounced melatonin surge at night.

Autonomic Nervous System Diseases↗

PubMed2003

Diabetic autonomic neuropathy.

Diabetic autonomic neuropathy is the most common and troublesome complication of diabetes mellitus. Although involvement of the autonomic nervous system is generally diffuse, symptoms may be confined to a single target organ or organ system. Complications of diabetic autonomic neuropathy contribute greatly to the morbidity, mortality, and reduced quality of life of the person with diabetes and are the major source of increased costs of caring for the diabetic patient. Factors in the pathogenesis of these complications are altered metabolism, vascular insufficiency, loss of growth factor trophism, and autoimmune destruction of nerves in a visceral and cutaneous distribution. The clinical manifestations and the complications of diabetic autonomic neuropathy are reviewed. Future therapeutic strategies that are developed from a better understanding of the pathogenetic processes underlying this disorder can be directed at the cause rather than the manifestations. There are studies in progress that suggest that autonomic nerves can be induced to regenerate, and the future for patients with diabetic autonomic neuropathy is brighter.

Animals↗