Vitamin D Study in Peril Over Avandia Concerns

From heartwire: Reported ambivalence about enrolling patients in the TIDE trial, a head-to-head study of rosiglitazone (Avandia; GSK) and pioglitazone (Actos; Takeda) in patients with type 2 diabetes, endangers the assessment of vitamin D supplementation.

That's because the GSK-funded and FDA-commissioned trial uses a 2-by-2 factorial design to answer 2 questions.

• Does long-term treatment with rosiglitazone or pioglitazone reduce the risk of vascular events?
• Does even longer-term treatment with vitamin D reduce the risk of death or serious cancer?

Quoted by heartwire, US principal investigator Jeffrey Probstfield said, "...I can tell you that probably at least half of the investigators in the US who signed up to do this [trial] find the vitamin D question more compelling and interesting than the rosiglitazone-vs-pioglitazone-vs-placebo issue."

If the trial is sidelined over enrollment problems (because of the controversy about rosiglitazone's safety), GSK is unlikely to support a trial assessing only vitamin D, Probstfield reasonably concluded.

A search of the NIH database reveals that, while there are several other studies assessing the possible health benefits of vitamin D, TIDE is the only trial examining the supplement's death- or cancer-preventing potential.

TIDE = Thiazolidinedione Intervention With Vitamin D Evaluation.