AIMS/INTRODUCTION: We evaluated the 24-h ambulatory blood pressure monitoring data of patients to investigate the relationship between the progression of diabetic polyneuropathy and impaired circadian blood pressure variability. MATERIALS AND METHODS: This study included 154 patients with diabetes who were hospitalized for hyperglycemic control. Routine biochemical and hematological tests, ambulatory blood pressure monitoring, screening for diabetic complications, nerve conduction studies, and Holter electrocardiography were carried out on all patients. They were classified according to the Baba classification and the clinical staging for diabetic polyneuropathy, and their ambulatory blood pressure monitoring data were compared. RESULTS: The patients were classified into stages 0 (n = 64), I (n = 42), II (n = 24), III (n = 11) and IV (n = 13) according to the Baba classification. As the severity of diabetic polyneuropathy progressed, the degree of nocturnal blood pressure reduction decreased and the percentage of patients with riser-type impaired circadian blood pressure variability increased. Similar results were observed in patients classified according to the clinical staging for diabetic polyneuropathy. In the multivariate logistic regression analysis, the severity of diabetic neuropathy and urinary albumin excretion were independently associated with the percentage of patients with riser-type. However, the adjusted odds ratio was the highest for Baba class I and decreased with increasing severity. CONCLUSIONS: Patients with progressive diabetic polyneuropathy and renal impairment often show impaired circadian blood pressure variability. The progression of electrophysiological and clinical neuropathy is associated with riser-type circadian blood pressure variability independent of urinary albumin excretion, insulin therapy, renin-angiotensin-aldosterone system inhibitor medication and body mass index.