Relationships between heart rate variability and urinary albumin excretion in patients with type 2 diabetes

Background. Although in type I diabetes the close association between heart rate variability and urinary albumin excretion (UAE) is recognized even in patients with normoalbuminuria, this association has not yet been fully established in patients with type 2 diabetes. Therefore, we investigated the association in patients with type 2 diabetes. Patients and Methods: All the hospital's 185 inpatients with type 2 diabetes were prospectively enrolled. Heart rate variability was evaluated by coefficients of variance of RR intervals (CVRR). Results: The mean age, duration of diabetes, and hemoglobin A(1C) of the patients were 59.7 +/- 9.9 years, 10.4 +/- 7.8 years, and 9.7 +/- 2.3%, respectively. An analysis of the patients showed a significant negative correlation between CVRR and log(10)-transformed (log) UAE (R = -0.3340, P < 0.0001). CVRR showed a significant negative correlation with age, duration of diabetes, hemoglobin A,c, systolic blood pressure, diastolic blood pressure, and triglyceride level. Log UAE showed a significant positive correlation with body mass index, hemoglobin A,c, systolic blood pressure, diastolic blood pressure, total cholesterol, and triglyceride level. in the macroalbuminuric group (UAE above 300 mg/g creatinine; n = 57), although CVRR showed a significant negative correlation with log UAE (R = -0.3571, P = 0.0064), but in normoalbuminuric (UAE below 30 mg/g Cr; n = 79) and in microalbuminuric groups (30 to 300 mg/g Cr; n = 49), CVRR and log UAE showed no correlation. Conclusions: Our data suggest that in type 2 diabetes, the association between CVRR and UAE is significant only in patients with macroalbuminuria.