Type 2 diabetes raises the risk of kidney stones, and the drugs used to treat it do not all affect that risk the same way. A new-user study of commercially insured US adults matched 358,203 pairs starting either an SGLT2 inhibitor or a GLP-1 receptor agonist and followed them a median of 192 days [1]. It is a large, well-built comparison, and it is worth reading carefully because the headline most people take from it is the wrong one — the same way a headline price is usually the wrong figure on a seller’s own page.
What was measured
Nephrolithiasis occurred at 14.9 events per 1,000 person-years in the SGLT2 arm against 21.3 in the GLP-1 arm, a hazard ratio of 0.69 (95% CI 0.67 to 0.72) and a rate difference of −6.4 per 1,000 person-years (95% CI −7.1 to −5.7). A second comparison, against DPP4 inhibitors, ran 14.6 against 19.9 per 1,000 person-years, at a hazard ratio of 0.74 (95% CI 0.71 to 0.77). The association held across sex, race and ethnicity, chronic kidney disease history and obesity.
The direction of the claim
This is a study about SGLT2 inhibitors. The GLP-1 arm is what they were measured against, so what it supports is that SGLT2 use came with fewer stones than GLP-1 use. It cannot say whether a GLP-1 raises the stone rate above no treatment at all, because no untreated group was followed. Reading it the other way round would be the same error as treating a roster-relative figure as an absolute one, which is a habit we have had to design against across the gout comparison and elsewhere.
The effect was also larger in adults under 70 than in those 70 or older, where the hazard ratio was 0.85. A difference that moves with age is a reminder that a pooled figure describes nobody in particular.
What to do with it
Nobody should switch drug classes over this, and no telehealth seller is choosing between them on a buyer’s behalf — the sellers on this site dispense GLP-1 medications and nothing else, which is itself the point. If stones are part of your history, it belongs in the intake, and whether the service you are paying makes a clinician reachable to discuss it is a question worth asking first. We keep the version of that question worth sending in questions they leave open, and what each seller discloses about its prescriber in what sellers do not publish.