Hypertension in diabetes: is there a place for age-adjusted centile cut-offs in those aged <50 years?

BACKGROUND Conventional cut-offs for hypertension are arbitrary, and vascular complications can occur below these values, particularly in diabetes. AIM To evaluate systolic blood pressure (SBP) distribution in diabetes and control populations, comparing hypertension prevalence using either conventional cut-offs (140 and 160 mmHg) or age-adjusted centile (75(th) and 90(th)) cut-offs derived from the control population. METHODS We compared 2521 individuals with diabetes to 5809 controls, after excluding those on anti-hypertensives and with established vascular disease in both groups. RESULTS Diabetic individuals were older (mean +/- SD 56 +/- 16 vs. 43 +/- 16years, diabetes vs. controls), and had higher BMI (29 +/- 5 vs. 24 +/- 4 kg /cm(2)) and SBP (145 +/- 23 vs. 131 +/- 18 mmHg, all p < 0.001). These factors were adjusted for in subsequent analysis. SBP rose with age and was also significantly higher in the diabetes group. In diabetes, conventional cut-offs indicated less hypertension in those aged < 50 years, compared to age-adjusted centile cut-offs. In age bands 18-29, 30-39, 40-49, 50-59, 60-69 and >70 years of the diabetes group, 24%, 33%, 43%, 62%, 70% and 74%, respectively exceeded 140 mmHg, compared to 35%, 44%, 43%, 45%, 40% and 27% exceeding the control-derived 75(th) centile value. DISCUSSION The use of control-derived age-adjusted cut-offs may provide an alternative approach to define hypertension in diabetes that may be of particular relevance to younger patients, although this would require validation against outcomes.