The uncertainty arises from the findings of the large randomised controlled ALLHAT 2002 trial (31 512 people 55 years or older with hypertension and one other risk factor for cardiovascular disease), in which the thiazide-like diuretic chlortalidone seemed to increase some cardiac risk factors, including the rate of developing diabetes. After four years of follow-up in those who had a normal fasting blood glucose at baseline, 302 (11.6%) people taking chlortalidone, 154 (9.8%) of those taking amlodipine (a calcium channel blocker), and 119 (8.1%) of those taking lisinopril (an angiotensin converting enzyme inhibitor) had fasting blood glucose concentrations of ≥7 mmol/l (P<0.001).1 Diuretics are known to achieve long term cardiovascular results as good as, or better than, alternative antihypertensives—at least in people aged 55 years or older. But clinicians may not initially treat patients with prediabetes and hypertension with a diuretic because they worry that the induced diabetes might result in a worse outcome than if they prescribed a different class of antihypertensive.