In treated hypertensive patients, a self-reported history of diabetes is a more powerful predictor of cardiovascular events than baseline or in-treatment blood sugar levels.
To determine the relation of self-reported history of diabetes as well as baseline and in-treatment blood sugar to subsequent cardiovascular disease (CVD) in treated hypertensive patients, we assessed the experience of 6886 participants in a systematic treatment program. The presence or absence of a history of diabetes was known for all patients, who were then stratified into 3 groups according to blood sugar at baseline and in treatment (/=7.75 mmol/L). Some 7.4% of all patients reported history of diabetes, and the overall prevalence of blood sugar >/=7. 75 mmol/L was 7.7% and 10.4% at baseline and in treatment, respectively. Patients with a history of diabetes were 10 or 8 times as likely to have blood sugar >/=7.75 mmol/L at baseline (47.2% versus 4.5%) or in treatment (55.0% versus 6.8%), as were patients without history. During an average 6.3 years of follow-up, patients with history of diabetes had a cardiovascular event incidence 2-fold higher than those without history (20.8 versus 8.6/1000 person-years). Age-gender-adjusted CVD incidence rate but not non-CVD was twice as high in the highest compared with the lowest blood sugar stratum (baseline 16.6 versus 8.4/1000 person-years; in treatment 15.2 versus 8.2). Three separate models of Cox multivariate analysis revealed that history of diabetes (with no history as reference) had a greater association with CVD events (hazard ratio 2.37, 95% confidence interval 1.80 to 3.11) than did baseline (1.75, 1.31 to 2.33) or in-treatment blood sugar (1.55, 1. 19 to 2.02). Furthermore, in the presence of history of diabetes (2. 15, 1.58 to 2.92), neither baseline nor in-treatment blood sugar was independently associated with CVD risk. In the elevated (>/=7.75 mmol/L) in-treatment blood sugar group, the age-gender-adjusted rate of CVD events in frequent diuretic users (30.79/1000 person-years) was significantly higher than in moderate (13.34, P=0.004) and rare users (13.25, P=0.008). These data affirm that the coincidence of diabetes and hypertension is common, that evidence of diabetes substantially increases CVD risk, that self-reported history is a more powerful predictor of CVD events than any measure of blood sugar, and that CVD increases in hypertensive diuretic users who develop hyperglycemia even when blood pressure is well controlled.
Alderman et al. (1999) studied this question.