Fish oil supplements—the most commonly used type of omega-3 supplements—contain oil that comes from the tissues of fatty fish, like mackerel, herring, tuna, and salmon. Although omega-3 supplements are effective for lowering triglycerides and may support cognition, the research on whether they impact blood sugar is mixed.
Overall, omega-3 supplements appear to have little to no effect on blood sugar levels; research has been inconclusive:
A 2024 review analyzed 35 research articles on omega-3s and diabetes (type 1, type 2, and gestational diabetes), in which participants took omega-3 supplements of various types, doses, and lengths of time. Researchers found that some participants saw a reduction in fasting blood glucose levels, while others did not.
A 2022 review analyzed 30 studies evaluating the effects of omega-3 supplementation on diabetes in humans. Researchers found that the supplements had a “significant effect on the reduction of fasting blood glucose.”
A 2020 meta-analysis of 12 randomized controlled trials found that people with diabetes who took fish oil supplements had no significant difference in glucose control outcomes compared to those who took a placebo.
A 2019 systematic review in The BMJ—the largest of its kind, including 83 randomized controlled trials—determined that increasing omega-3 intake had little or no effect on blood glucose levels or preventing or treating type 2 diabetes.
Omega-3 supplements shouldn’t be your first choice to manage blood sugar, according to experts in the field.
“In general, omega-3 supplements seem to be mostly blood sugar-neutral,” registered dietitian and diabetes expert Vandana Sheth, RDN, CDCES, FAND, told Health. “Across multiple large reviews, most studies show little to no meaningful change in HbA1c or fasting glucose.”
According to registered dietitian Erin Palinski-Wade, RD, CDCES, omega-3s may slightly help blood sugar indirectly “by lowering long-term low-level inflammation”—but that the supplements still have “small or mixed effects on blood sugar tests.”
“Omega-3s are not recommended for glycemic control,” added Andres Splenser, MD, endocrinologist at Memorial Hermann Health System in Houston, “But they may be used for triglyceride-lowering or cardiovascular risk in some patients.” (Diabetes can increase the risk of cardiovascular disease, so consuming enough omega-3s can help reduce overall risk, said Palinski-Wade.)
Considering omega-3s’ modest-to-neutral effects on blood sugar, it’s best to discuss with your doctor whether they’re worth adding to your supplement routine.
Public health organizations like the American Diabetes Association don’t specifically recommend omega-3s in their guidelines for blood sugar management.
If you decide to take omega-3 supplements for whatever reason, a typical dose of under 3 grams per day is generally safe. “High doses (over 3 grams per day) can increase bleeding risk, especially with anticoagulants or antiplatelet drugs,” said Splenser.
People with fish or shellfish allergies should avoid fish-based supplements, he added, and those with atrial fibrillation or flutter may have a higher risk of arrhythmia with high doses of EPA/DHA.
Pregnant women and people with liver conditions should also take special care. “Cod liver oil and other omega-3 products that are high in vitamin A can lead to vitamin A toxicity, which is especially risky during pregnancy or for people with liver conditions,” Palinski-Wade said.
If possible, a food-first approach for omega-3s is ideal. “Try incorporating fatty fish or plant-based sources like chia, flax, or hemp into your diet,” said Palinski-Wade.
“For blood sugar balance, it’s not a single nutrient that has the biggest impact,” she added. “It is a combination of fiber-rich meals, adequate protein, heart-healthy fats, strength training, moving after meals, and sleep.”
