Prospective study of autonomic neuropathy as a predictor of mortality in patients with diabetes

The objective of this study is to evaluate whether autonomic neuropathy predicts short term all-cause mortality in an elderly cohort of veteran patients with diabetes.

All of the diabetic patients receiving primary care at one VA medical center were eligible for participation, between 1990 and 1997. One thousand and fifteen patients were identified, of whom 14% declined to participate, so that a total of 843 diabetic patients were enrolled. Autonomic neuropathy was evaluated by heart rate response to timed deep breathing. One hundred and fifty one patients have died since the onset of the study.

Mean follow-up was 42.4 months. Subjects who died had greater diabetes duration compared with survivors (13.1 vs. 11.4 years, P=0.04) but were comparable with regards to type of diabetes and mean glycosylated hemoglobin level. The Cox proportional hazards analysis, adjusting for age, smoking status, creatinine, pack-years of cigarettes smoked, diabetes duration, race, history of ischemic heart disease and hypertension showed that those patients with the lowest quintile of heart rate variability had a significantly increased risk of mortality (hazard ratio=1.49, 95% confidence limits 1.01-2.19).

This study supports the hypothesis that decreased heart rate variability is an independent risk factor for mortality in diabetic patients followed in a primary care setting.