Reduced efficacy of blood pressure lowering drugs in the presence of diabetes mellitus—results from the TRIUMPH randomised controlled trial

We investigated whether diabetes mellitus (DM) affects the efficacy of a low-dose triple combination pill and usual care among people with mild-moderate hypertension. TRIUMPH (TRIple pill vs Usual care Management for Patients with mild-to-moderate Hypertension) was a randomised controlled open-label trial of patients requiring initiation or escalation of antihypertensive therapy. Patients were randomised to a once-daily low-dose triple combination polypill (telmisartan-20mg/amlodipine-2.5 mg/chlorthalidone-12.5 mg) or usual care. This analysis compared BP reduction in people with and without DM, both in the intervention and control groups over 24-week follow-up. Predicted efficacy of prescribed therapy was calculated (estimation methods of Law et al.). The trial randomised 700 patients (56 ± 11 yrs, 31% DM). There was no difference in the number of drugs prescribed or predicted efficacy of therapy between people with DM and without DM. However, the observed BP reduction from baseline to week 24 was lower in those with DM compared to non-diabetics in both the triple pill (25/11 vs 31/15 mmHg, p ≤ 0.01) and usual care (17/7 vs 22/11 mmHg, p ≤ 0.01) groups, and these differences remained after multivariable adjustment. DM was a negative predictor of change in BP (β-coefficient −0.08, p = 0.02). In conclusion, patients with DM experienced reduced efficacy of BP lowering therapies as compared to patients without DM, irrespective of the type of BP lowering therapy received.