ARIC Study: Examining Hypertension Risk Based on A1C

Bower JK, Appel JL, Matsushita K, et al. Glycated hemoglobin and risk of hypertension in the Atherosclerosis Risk in Communities Study.
Diabetes Care. 2012;35:1031-1037. 

Bower and colleagues examined the role of A1C as a predictor of hypertension among subjects with and without diabetes in the Atherosclerosis Risk in Communities (ARIC) study.  

Subjects enrolled in ARIC, a community-based cohort study, completed 3 follow-up examinations at approximately 3-year intervals over the study period. As A1C levels were obtained at visit 2, the current study considers visit 2 the baseline visit. Subjects with data at visit 2 (N=9,603) were aged 45–64 years, had no hypertension at baseline, were African-American or Caucasian race only, and had mean A1C 5.6%. The maximum follow-up time was 18 years. Blood pressure (BP) was obtained at each visit; use of antihypertensive medications was also assessed via medication inventory. Presence of hypertension was assessed via annual telephone calls after the last follow-up examination was conducted.  

The association between baseline A1C and incident hypertension was estimated using Cox proportional hazards models based on two definitions over varied follow-up periods: self-reported hypertension (per medication use at follow-up visits, or medication use or hypertension diagnosis divulged during annual phone calls), over ≤18 years follow-up and measured BP (avg systolic ≥140 mmHg; avg diastolic ≥90 mmHg) or use of hypertension medication at follow-up visits (visit-based hypertension), over ≤9 years follow-up.  

The number of subjects with or without diabetes who had hypertension was as follows:  

Self-reported hypertension  

No diabetes at baseline: n=4,800  

Diabetes at baseline: n=377  

Visit-based hypertension  

No diabetes at baseline: n=1,670  

Diabetes at baseline: n=119  

Self-reported hypertension incidence was 45 cases/1,000 person-years over a median follow up of 12 years among those with no diabetes at baseline; 76 cases/1,000 person-years over median follow-up of 9 years among those with diagnosed diabetes at baseline. Visit-based hypertension incidence was 43 cases/1,000 person years among those with no diabetes at baseline; 62 cases/1,000 person-years among those with diagnosed diabetes at baseline.  

Among those with or without diabetes, elevated baseline A1C levels were associated with increased hypertension risk. When data for subjects with prevalent diabetes with poor glycemic control (defined as A1C ≥7% vs <7%) were examined, these subjects were at 1.25 times increased risk for incident hypertension (95% confidence interval [CI], 1.01–1.56). A1C levels in the prediabetic range (5.7–6.4%) were independently associated with both incident self-reported hypertension (hazard ratio [HR], 1.14; 95% CI, 1.06–1.23) and visit-detected hypertension (HR, 1.17; 95% CI, 1.03–1.33) among subjects without diabetes vs those with A1C <5.7%.  

 

July 2012 

This overview was created by KnowledgePoint360 Group, LLC, and was not associated with funding via an educational grant or a promotional/commercial interest. 

Related content: 

Read more about this study and additional cutting-edge diabetes data in the May 2012 issue of Clinical Insights® in Diabetes. Click here. 

ARIC: Role of A1C in Predicting Hypertension—Design  

ARIC: Role of A1C in Predicting Hypertension—Results  

Last Modified: 11/15/2013