A study on humans examined the effects of grape seed oil on diabetes-related markers, and the results are encouraging.
Overweight or obese women were randomly assigned to consume grape seed oil or sunflower oil for 8 weeks, as part of a weight loss diet. Grape seed oil reduced insulin resistance and inflammation, whereas sunflower oil did not.80
When buying grape seed oil, make sure it’s edible, because it’s also sold as a skin care product, which would be inappropriate to eat, although some products can be used for both purposes.