Summary: In women with type 2 diabetes on metformin, 52 weeks of sitagliptin preserved total proximal femur bone density relative to placebo (T-score difference 0.11; p=0.0063), without affecting glycaemic control and with no serious adverse events, though no benefit was seen at other skeletal sites.
PICO Summary
| Element | Detail |
|---|---|
| Population | 132 women with type 2 diabetes on stable metformin monotherapy, Italy (phase III, double-blind). |
| Intervention | Oral sitagliptin for 52 weeks, plus background metformin. |
| Comparison | Identical placebo for 52 weeks, plus background metformin. |
| Outcome | Sitagliptin preserved total proximal femur BMD T score (between-group difference 0.11; 95% CI 0.03–0.19; p=0.0063); placebo declined significantly. No change at other sites or in bone turnover markers. Reduced inflammatory mediators. No glycaemic difference; adverse events mild and balanced. |
SLowDOWN trial
RCT · T2D women · 52 weeks
Over 52 weeks, sitagliptin preserved total hip bone density where placebo declined, a small but significant T-score difference. No benefit at other sites and no effect on glycaemia.
Expert Commentary
The elevated fracture risk in type 2 diabetes, despite often-normal density, is a real and underappreciated problem, so a dedicated randomised trial of a glucose-lowering drug with bone as the primary endpoint is genuinely welcome, and rarer than it should be. The verdict is mildly favourable: sitagliptin preserved hip density where placebo lost it, the mechanism via incretin effects on bone is plausible, and it fits the wider picture of DPP-4 inhibitors being skeletally neutral-to-favourable, in clear contrast to glitazones and the SGLT2 fracture signal. I keep my enthusiasm proportionate, though. The effect was a 0.11 T-score difference at one site among several measured, with no change in turnover markers, over only 52 weeks, and it rests on a surrogate rather than actual fractures. Can I use this with my patients? Yes, in a specific way: for a postmenopausal woman with diabetes and fracture risk who needs a step beyond metformin, this reassures me that sitagliptin is at least skeletally safe and perhaps mildly helpful. But I would never prescribe it for bone alone, and standard osteoporosis care, DXA, FRAX, calcium and vitamin D, bone-specific therapy, continues regardless.
References
Barchetta I, Filardi T, Dule S, et al. Effect of sitagliptin vs. placebo on bone mineralization in women with type 2 diabetes: the SLowDOWN (SitagLiptin in Diabetes for Osteoporosis in WomeN) randomized clinical trial. BMC Med. 2025;23(1):562. doi:10.1186/s12916-025-04363-w