Summary: In a 24-week trial in adolescents and young adults with type 1 diabetes, neither a low-carbohydrate nor a Mediterranean diet produced significant changes in bone turnover markers, with the differences between diets not statistically significant in this exploratory analysis.
PICO Summary
| Element | Detail |
|---|---|
| Population | 40 individuals aged 12–21 with type 1 diabetes (20 per group); 24-week randomised controlled trial, Israel. |
| Intervention | A low-carbohydrate diet (median 86 g carbohydrate/day). |
| Comparison | A Mediterranean diet (median 130 g carbohydrate/day). |
| Outcome | Bone turnover markers did not change significantly: CTX went from 395 to 423 pg/mL on low-carb (p=0.278) and 357 to 296 on Mediterranean (p=0.245); P1NP changes were also non-significant (p=0.056 and p=0.594). Lower calcium and magnesium intake and BMI z-score on low-carb did not survive false-discovery-rate correction. Only adjusted alkaline phosphatase fell significantly in the low-carb group (p=0.009). The authors concluded differences were insignificant. |
Low-carb vs Mediterranean diet and bone turnover in type 1 diabetes
RCT · type 1 diabetes · 24 weeks
Over 24 weeks neither diet significantly changed bone turnover markers (CTX or P1NP), and between-diet differences were not significant. An exploratory null result offering qualified reassurance, not evidence the diets differ for bone.
Expert Commentary
This is an exploratory study whose honest result is reassurance through a null finding, and it must be read that way rather than as evidence that the diets differ for bone. The question matters, because type 1 diabetes carries excess fracture risk that emerges early, adolescence is the window of peak bone-mass accrual, and low-carbohydrate diets raise theoretical concerns about acid load and reduced calcium intake. Against that backdrop, the key message is that over 24 weeks neither diet significantly changed the bone resorption marker CTX or the formation marker P1NP, and the apparent between-diet differences in mineral intake and BMI did not survive correction for multiple comparisons. The lone significant signal, a fall in alkaline phosphatase on low-carb, is of uncertain meaning. Limitations reinforce caution in both directions: only 20 per group, surrogate turnover markers rather than bone density or fractures, and just 24 weeks. Can I use this with my patients? Yes, as qualified reassurance. For a young person with type 1 diabetes choosing a low-carbohydrate diet for glycaemic reasons, this provides some short-term comfort that bone turnover was not adversely disturbed, while I would still ensure adequate calcium and vitamin D and recognise that longer studies with density and fracture endpoints are needed before firm conclusions.
References
Levran N, Levek N, Levy-Shraga Y, et al. Bone turnover markers (CTX and P1NP) following low-carbohydrate and Mediterranean diet interventions in adolescents and young adults with type 1 diabetes. Nutrients. 2025;17(24):3935. doi:10.3390/nu17243935