Autonomic imbalance found in comorbid diabetes/hypertension
MedWire News: The presence of Type 2 diabetes in individuals with treatment-resistant hypertension is associated with autonomic imbalance (AI), lower adiponectin levels, and higher body mass index (BMI), a Brazilian study has found.
The researchers say their study supports the hypothesis that AI is a common pathogenic mechanism underlying the development of hypertension and Type 2 diabetes.
Leandro Boer-Martins (State University of Campinas, Sao Paolo, Brazil) and co-workers studied 25 individuals with treatment-resistant hypertension, 10 of whom also had Type 2 diabetes. Patients underwent a range of assessments, including echocardiogram and 24-hour ambulatory electrocardiography to assess heart rate variability (HRV).
Interestingly, levels of fasting glucose and glycated hemoglobin (HbA1c) were not significantly different between diabetic and supposedly "nondiabetic" individuals. Both groups also exhibited marked disruption of their circadian rhythms, with inverted sympathetic/parasympathetic tones during the day and night.
Some characteristics did differ between the groups, however, with diabetic individuals having significantly higher mean BMI (33.7 vs 26.6 kg/m²), higher serum triglycerides (254.8 vs 108.6 mg/dl), and lower adiponectin levels (6729.7 vs 10911.6 ng/ml) compared with nondiabetic individuals.
Furthermore, the diabetic group had greater AI, as indicated by a raft of HRV parameters, compared with nondiabetic patients. HRV was significantly positively correlated with serum adiponectin and negatively correlated with HbA1c.
Writing in Cardiovascular Diabetology, the researchers note that the similar pattern of circadian disruption in diabetic and nondiabetic patients "indicates the importance of lifestyle behavior in the genesis of resistant hypertension."
Despite circadian disruption, however, autonomic function was better-preserved in hypertensive patients without diabetes than in those with diabetes.
They conclude: "A better comprehension of the patterns of autonomic imbalance and circadian disruption in resistant hypertension is one more parameter to guide clinicians towards a holistic treatment of hypertension and diabetes."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Joanna Lyford