Cardiovascular Autonomic Neuropathy Is Associated With Microalbuminuria in Older Patients With Type 2 Diabetes

Abstract

OBJECTIVE—Cardiovascular autonomic neuropathy is associated with microalbuminuria in young and middle-aged patients with type 2 diabetes. We examined this relationship and the potential mediating role of blood pressure in older patients. RESEARCH DESIGN AND METHODS—At least two of three components of cardiovascular autonomic testing were completed by 132 patients (mean age 70 ± 5.6 years). Relative rankings on each of the components were averaged to create a summary heart rate variability (HRV) measure. The urine microalbumin-to-creatinine ratio (milligrams albumin/grams creatinine) was calculated. Blood pressure was measured at rest and by 24-h ambulatory recording. RESULTS—Urine microalbumin-to-creatinine ratio was higher in those with lower HRV (mean urine microalbumin-to-creatinine ratio 28, 56, and 191 mg/g from the highest to lowest tertile of HRV; P < 0.0001). Resting and ambulatory blood pressure levels were negatively correlated with HRV and positively correlated with urine microalbumin-to-creatinine ratio. In multivariate analysis adjusting for age, duration of diabetes, HbA1c, and HDL cholesterol, HRV and blood pressure were both independently associated with urine microalbumin-to-creatinine ratio, with no evidence that either mediates the effect of the other. CONCLUSIONS—Cardiovascular autonomic neuropathy and blood pressure are independently associated with microalbuminuria in older patients with type 2 diabetes.