Nighttime BP in elderly individuals with prediabetes/diabetes with and without CKD: The HEIJO-KYO study

Abstract

Background and objectives Although previous studies suggested that nighttime BP is elevated in diabetes mellitus, the association between prediabetes and nighttime BP remains unclear. In addition, the relationship between diabetic status, renal function, and nighttime BP has not been evaluated in large populations. Design, setting, participants, & measurements In this cross-sectional study, we assessed diabetic status, renal function, and ambulatory BP parameters among 1081 community-dwelling elderly individuals (mean age, 71.8±7.0 years). Participants were classified into six categories based on diabetic status (normoglycemia, prediabetes, or diabetes mellitus) and renal function (normal function or CKD). BP was measured at 30-minute intervals for 48 hours using a validated ambulatory recorder. Results The mean nighttime systolic BP (SBP) was 115.7±16.1 mmHg. The multivariable analysis, adjusted for age, sex, smoking status, and daytime SBP, revealed that, compared with participants with normoglycemia but without CKD (n=378), mean nighttime SBP was significantly higher in participants with both prediabetes and CKD (n=93) by 2.9 mmHg (95% confidence interval [95% CI], 0.2 to 5.6; P=0.03) and in patients with both diabetes mellitus and CKD (n=30) by 7.8 mmHg (95% CI, 3.5 to 12.2; P<0.001) but not in participants with both normoglycemia and CKD (n=75), participants with prediabetes without CKD (n=374), or patients with diabetes mellitus without CKD (n=131). Notably, the multivariable analysis indicated that the interaction terms of diabetic status and renal function were significantly associated with nighttime SBP (P=0.03). Conclusions Nighttime SBP was significantly higher in participants with prediabetes and CKD but not in participants with prediabetes without CKD, compared with participants with normoglycemia and without CKD. In addition, a significant interaction effect of diabetic status and renal function on nighttime SBP was detected in a general elderly population.