That trick never works.
Q: So, have you seen the article about Vitamin D and diabetes?
A: Of course. The tireless staff of StatsChat read even West Island newspapers. It’s a good report, too.
Q: What did the researchers do?
A: They studied 5200 people without diabetes, following them up for five years. 199 of them developed diabetes. The people who ended up with diabetes started off with lower vitamin D levels in their blood.
Q: Where did you get those details?
A: The abstract for the study publication (you can also get the full text there free if you’re at a university or if you wait until next year).
Q: Isn’t it annoying that newspaper websites don’t provide any links to that sort of information?
A: It’s like you’re reading my mind.
Q: One of the study authors is quoted as saying “”It’s hard to underestimate how important this might be.” What do you think?
A: I think he meant “overestimate”.
Q: So, how important is this finding?
A: If it really is an effect of vitamin D, it would be really important. A simple supplement would be able to dramatically reduce the risk of diabetes.
Q: How can we tell?
A: Someone needs to do a randomized trial, where half the participants get vitamin D and half get a dummy pill. If the effect is real, fewer people getting vitamin D will end up with diabetes.
Q: That sounds like a good idea. Is someone doing a trial?
A: Yes, Professor Peter Ebeling, of the the University of Melbourne.
Q: Is there some useful website where I can find more information about the trial?
A: Indeed.
Q: Will it work?
A: No.
Q: Are you sure?
A: No, that’s why we need the trial. But it’s a trial of vitamin supplementation, which almost always has disappointing results, and it’s a trial in adult-onset diabetes, which almost always has disappointing results.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »