This 2018 analysis, published in PLOS Medicine, combined data from 16 prospective cohort studies across 12 countries to investigate the relationship between dairy fat consumption and type 2 diabetes (T2D). Rather than relying on participants to recall what they ate, researchers measured three fatty acids in blood or tissue that are associated with dairy fat consumption. The analysis included 63,682 adults without diabetes at baseline, of whom approximately 15,180 developed T2D during an average of nine years of follow-up.

Higher concentrations of all three fatty acid biomarkers were associated with a lower risk of developing T2D. Comparing participants with higher versus lower combined biomarker levels, researchers found a 29% reduction in relative risk. These associations persisted after adjusting for several potential confounding factors, including obesity, physical activity, and other metabolic risk markers.

There are important limitations, however. Although measuring fatty acids avoids the inaccuracies of self-reported dietary intake, these biomarkers are not exclusive to dairy and can be influenced by other foods and metabolic processes. Results also varied considerably between studies. Most importantly, this was an observational analysis, so it cannot establish that consuming dairy fat prevents diabetes. The results nevertheless raise questions about dietary recommendations favoring low-fat dairy and provide a basis for further controlled research.

https://pmc.ncbi.nlm.nih.gov/articles/PMC6179183/