Magical Mango Thinking About Preventing Diabetes

“This high-sugar fruit may actually lower diabetes risk‚” says the press release from George Mason University. Lately, breathless headlines have bombarded us with magical mango thinking about preventing diabetes with this delicious fruit. Food is medicine, right?

Well, not really. Food is food. Medicine is medicine. And the study that props up these sensational headlines doesn’t actually study diabetes prevention.

Mangoes vs Granola Bars

Looking beyond the headlines, we find a randomized controlled study of mangoes versus honey and oats granola bars in 24 persons with prediabetes. The duration of the study is only 24 weeks. For their study protocol, researchers defined five primary outcome measures related to glycemic control: fasting glucose, fasting insulin, HbA1c, HOMA-IR, and HOMA-β. They found improved outcomes on some but not all of them for people in the mango group.

We have concerns about the control group. First of all, they do not appear to be well-matched. The most obvious difference is that virtually all (10/11) of the mango group is female. In the control group, seven are female and five are male. Then there is the issue of baseline insulin sensitivity (derived by QUICKI). It is higher in the mango group than in the control group. The authors claim that this difference is not significant, but they do not explain how they determined this. The error bars in their graph of values over time (fig. 1) leave a different impression.

Fundamentally, though, we have a problem with the choice of the control. To prove that mangoes themselves prevent could diabetes, a sugary granola bar is not really a placebo control. Without a doubt, asking people to eat a serving of honey and oats granola bars every day for 24 weeks, in addition to their regular diet, will have an effect of its own on blood sugar.

Diabetes Prevention?

But the real problem with claiming a benefit for diabetes prevention is that this study did not study the onset of diabetes.

So do mangoes prevent diabetes? Not likely. Not all by themselves.

Are they a better snack than sugary granola bars? Probably so.

Click here for the study and here for the puffed-up press release. For a more balanced perspective, click here.

Mango, photograph by Ivar Leidus, licensed under CC BY-SA 4.0

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October 7, 2025