More than a decade ago, large data reviews found that using drugs to tightly control blood sugar in people with type 2 diabetes does more harm than good. In careful studies, it didn’t save lives, reduce heart problems, or prevent kidney failure. And while on rare occasions it helped to avoid or delay limb amputations (1 in 250 people), forty times more often it caused life-threatening episodes of low blood sugar (1 in 6 people).
These findings, and the fact that newer drugs prevent heart problems and deaths independent of glucose lowering, have led to a merciful shift away from obsessing over sugar levels. As a former ER doc, I saw countless hypoglycemic episodes—some of them tragic—during the era of “tight glycemic control.”
[To read about one strange case, check out this post from last year.]
So when I saw the New York Times headline, “Controlling Blood Sugar Cut Heart Disease Risk in Half, Study Says,” I was concerned. Predictably, however, the Times has virtually everything about the study wrong. Less predictably, so do the study’s authors.
The Times writer claims the new study, published this week in a Lancet journal, highlights the effects of treatment to lower glucose. It doesn’t. In actuality, the study compared long-term (20-year) outcomes among people with borderline diabetes in two trials that started in the ’90s. Both compared lifestyle changes and pills with no treatment, but found mostly small differences in progression to diabetes. The new paper, however, did a post hoc secondary analysis comparing participants whose sugars normalized in the first year with those whose didn’t, and tracked heart problems.
In other words, the researchers compared people whose abnormal sugars quickly resolved—regardless of treatment, including in the placebo group—with people whose sugars stayed too high. And what did they find?
Extra! Extra! Read all about it!! We got a doozy, folks: People who were healthier twenty years ago were sometimes healthier today, too.
Science!!!
Which brings us to the Times headline: “Controlling Blood Sugar Cut Heart Disease Risk in Half.” For starters, the new study didn’t look at ‘controlling’ sugar. That would be treatment, and the study didn’t compare outcomes based on treatment; it compared outcomes based on changes in sugar irrespective of treatment. Then the writer uses a relative number—“cut in half”—rather than an absolute number, to glaze the result. BTW, for a one-minute primer on absolute vs. relative risk, see our new video, posted last week.
So what was the absolute number that was cut in half? It was 7%. Which is pretty amazing. Only 7% of people with persistent prediabetes or diabetes went on to have a heart problem over twenty years. For those whose sugar resolved immediately, it was about 3%. That is a 4% difference. That is the difference the researchers tout, the journalist trumpets, and readers are supposed to be impressed by: 4%.
Yay?
I mean, dude. The New York Times has GOT TO LEARN HOW TO READ A STUDY. So do the (Stanford and Johns Hopkins) doctors who offered breathless quotes like “an incredible finding!” I realize it’s exciting to be asked to comment for the Times, but you need to read the study—and think, please—before you talk to a reporter.
To be fair to the journalist, the worst part is that the researchers who did the new study spun their results, and the editors and peer reviewers at Lancet allowed it. All parties ignored the paper’s methods (a secondary analysis of sugar levels, not treatment) and seem not to know the proven history of harms from treating numbers, rather than people. This illiteracy across the scientific and lay-press ecosystem is what allowed and amplified the study’s wrongheaded conclusion. The researchers’ conclusion statement was: “Targeting remission might represent a new approach to cardiovascular prevention.”
New?!? Targeting low glucose levels is not new. It’s a failed and harmful approach. And it’s not what their study tested. The study tested what happens to people whose prediabetes quickly disappeared—spontaneously, treatment-related, or otherwise. The answer was 4% fewer heart problems, twenty years later.
So thank you, NYT, for always offering deranged, uneducated, misleading research translation. And thank you, Lancet, for the same. Couldn’t do it without you.
For a little more depth, check out the podcast.
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