Researchers analyzed results from 10 human studies following about half a million adults. In the observational cohort studies, people who used the most olive oil were about 13 percent less likely to develop type 2 diabetes than those who used the least. In the randomized trials, the reduction was about 22 percent. The signal was stronger for extra‑virgin olive oil, about 25 percent lower risk.

The clearest benefit appeared at 10 to 20 grams a day (roughly 1 tablespoon). Intake above 20 grams did not show extra benefit in this analysis. The pool combined long‑term population research with shorter clinical trials, which points to a consistent picture across study types.

Olive oil, especially extra‑virgin, provides monounsaturated fat and plant polyphenols that can improve insulin sensitivity and calm low‑grade inflammation. Swapping it for butter, margarine, or creamy dressings can steady after‑meal blood sugar and support heart health over time. These combined studies show a strong association, not final proof that olive oil alone prevents diabetes, but the pattern is consistent with prior reviews.

People who regularly used about one tablespoon of extra‑virgin olive oil each day had a lower chance of developing type 2 diabetes, with no added benefit seen above that range in this analysis.

To apply this study to your own life, start by replacing one daily use of butter, margarine, or vegetable oil with high‑quality olive oil instead. Use it to sauté, drizzle, or dress your food, keeping the portion around a tablespoon. If you are tracking blood sugar, notice how your numbers change over a few months. Small, steady swaps can add up over time.

Source: Ghavami A, et al. (2024), Journal of Health, Population and Nutrition.