Heartburn pills may quietly lower blood sugar

Proton pump inhibitors are among the most commonly prescribed drugs anywhere, taken long term by huge numbers of people for reflux and other acid-related disorders. Emerging evidence has hinted that they may also influence glucose metabolism, which would matter twice over: as a possible bonus for people with type 2 diabetes, and as something prescribers and patients should track when the drugs are started or stopped. This review set out to quantify what PPI use does to fasting glucose, HbA1c and insulin resistance in people with and without type 2 diabetes.

The reviewers searched PubMed, the Cochrane Library, Embase and Scopus for randomised trials and observational studies reporting fasting blood glucose, HbA1c or insulin resistance with PPI use, then pooled results with a random-effects model. Fifteen studies involving 2,038 participants were included: nine studies with 1243 participants fed the fasting glucose analysis, seven with 1121 covered HbA1c, and four with 412 examined insulin resistance. Study quality was formally assessed, and the authors note the review was not prospectively registered.

PPI use was associated with a significant 5.32 mg/dL reduction in fasting blood glucose. HbA1c fell in some studies, but the findings were inconsistent across the seven studies reporting it, and there was no significant effect on insulin resistance. Subgroup analyses suggested the benefit was larger in people with poorly controlled type 2 diabetes. Reported adverse events were mild, mainly gastrointestinal symptoms and headache, though small samples and moderate risk of bias in some trials limited the certainty of the evidence.

The result adds quantitative weight to a curious pharmacological side story: acid-suppressing drugs may nudge glucose control, perhaps enough to notice in poorly controlled diabetes. But the evidence is fragile, with small studies that disagreed with each other and a review that was never registered in advance, and the long-term balance of benefit and risk with chronic PPI use remains unresolved. Larger, properly registered trials in people with diabetes would be needed before this becomes more than a footnote.

If you take a PPI and also watch your blood sugar, this pooled evidence suggests the drug may be shaving a little off your fasting glucose, which is worth knowing when readings shift after starting or stopping one. The authors suggest regular glucose monitoring may be sensible for people with diabetes on long-term PPI therapy. None of this is a reason to take a PPI for blood sugar: the effect is modest, the evidence shaky and the long-term picture unknown.