Trial finds diuretic use doubles diabetes risk
By Daniel Cressey
Diuretics are not suitable as first-line treatment for hypertension in as many as half of all patients with the condition, a new trial concludes.
A combination of thiazide diuretic and angiotensin receptor blocker more than doubled the risk of new-onset diabetes compared with a calcium channel blocker and ACE inhibitor.
The research comes as NICE prepares to give calcium channel blockers a much more prominent role in hypertension treatment in final guidance due next week.
The Star trial, presented at the European Hypertension Society meeting in Madrid last week, found even when prescribed with a maximum dose of ARB, diuretics gave impaired metabolic outcomes.
After 56 weeks of treatment, the rate of new-onset diabetes was 26.6 per cent in patients treated with hydrochlorothiazide and losartan, but only 11.0 per cent with trandolapril and verapamil.
The study of 240 patients found HbA1C control was worse in the diuretic group, while there was no difference in blood pressure control.
Study leader Dr George Bakris, vice-chair of the unit of preventive medicine at the Rush Medical University, Chicago, US, said first-line use of diuretics in patients who were insulin resistant – around half the total – was 'at best debatable'.
Professor Peter Sever, professor of clinical pharmacology and therapeutics at Imperial College London and a leader of the ASCOT study, said: 'The new NICE guidelines are going to state very clearly new-onset diabetes is a real phenomenon and there is a dramatic excess with ß-blockers and also with thiazide treatment.
'Although there is a potential for drugs that block the renin-angiotensin system to reduce it, it doesn't go away.'
Professor Sever, honorary consultant physician at St Mary's Hospital in London, said: 'The final [NICE] document will recommend "calcium channel blocker or thiazide diuretic" [for white over-55s].'
GP experts warned that long-term data was needed.
Dr John Ashcroft, a GP in Tibshelf, Derbyshire, and CHD lead for Erewash PCT, said: 'Long-term outcomes with low-dose thiazides appear to be good.'