Clinical Trial Evidence on Diet and Type 1 Diabetes Outcomes

A new systematic review of clinical trials has found that no single dietary pattern consistently improves blood sugar control or weight management in youth and adults living with type 1 diabetes. The findings highlight the urgent need for more rigorous research into precision nutrition strategies tailored to individual patient needs.

Researchers analyzed 12 studies comprised of 11 clinical trials conducted between 2011 and 2024, involving 668 youth and adults with type 1 diabetes. The studies compared various diet patterns including Mediterranean, low and moderate carbohydrate, low fat, and generally healthful diets. Outcomes that were pooled in meta-analyses included glycated hemoglobin (HbA1c) and weight. Results showed:

No consistent benefit of any specific diet pattern in randomized trials.

Low-carbohydrate diets in single-arm studies suggested improvements in HbA1c (−0.63% [95% CI, −0.99 to −0.27]), but evidence quality was graded as being very low.

Meta-analyzed results suggested the possibility of variation in response to diet patterns between individuals, based upon wide pooled confidence intervals.

However, dedicated studies are needed to evaluate whether true heterogeneity in response to diet patterns exists, which would indicate the need to tailor diets to individual characteristics in “precision nutrition” paradigms.

Despite these findings, most studies did not stratify results by participant characteristics such as age, sex, or baseline metabolic profile — limiting insights into who might benefit most from specific dietary approaches.

The study underscores the importance of determining whether diet approaches that account for interindividual differences in metabolism, lifestyle, and treatment goals are more effective than one-size-fits-all dietary recommendations.

Conclusion

High-quality randomized trials are needed to determine whether tailored nutrition recommendations will help to optimize glycemia and weight management in people with type 1 diabetes. Until strategies for determining the optimal diet for a given individual emerge, current recommendations to individualize diet counseling to individual and cultural preferences should continue to be followed.