Fatty, oily fish like salmon, sardines, and mackerel top the list for people with diabetes. These varieties are rich in omega-3 fatty acids, which support heart health and may improve how your body responds to insulin. Eating two to three servings per week (roughly 8 to 12 ounces total) is the sweet spot linked to the greatest health benefits.
Why Oily Fish Stands Out
Not all fish deliver the same benefits. A large population-based study found that people who ate oily fish at least twice a week had a 22% lower risk of developing type 2 diabetes compared to those who never ate it. Nonoily white fish like cod and tilapia showed no similar association. The difference comes down to omega-3 content: oily fish contain significantly more of the long-chain fatty acids EPA and DHA, which reduce inflammation and appear to improve how cells respond to insulin.
These omega-3s get incorporated into cell membranes, where they change the membrane’s physical properties and influence signaling pathways involved in blood sugar regulation. Breakdown products of DHA, called specialized proresolving mediators, help resolve the chronic low-grade inflammation that drives insulin resistance. In animal studies, these compounds improved both liver and muscle insulin sensitivity in a dose-dependent way.
The Best Fish to Choose
Salmon is the most widely recommended option. It’s high in omega-3s, widely available fresh or canned, and versatile enough to fit into most meals. A single 4-ounce serving delivers a substantial dose of healthy fats along with high-quality protein and virtually no carbohydrates, so it won’t spike your blood sugar.
Sardines are a close second and arguably more nutritious per ounce. They pack omega-3s, calcium, and vitamin D into a small, inexpensive package. Because sardines are tiny and low on the food chain, they accumulate very little mercury, making them safe to eat frequently.
Other strong choices include:
- Mackerel (canned): Very high in omega-3s and low in mercury. Avoid king mackerel, which is a larger species with higher mercury levels.
- Herring: Comparable omega-3 content to salmon, often sold smoked or pickled.
- Trout: A freshwater option that’s rich in omega-3s and consistently low in mercury.
- Anchovies: Tiny fish with concentrated omega-3s, easy to add to sauces and salads.
White Fish Still Has a Place
Lean white fish like cod, tilapia, flounder, and pollock don’t offer the same omega-3 punch, but they’re excellent sources of protein with almost no saturated fat. They won’t raise your blood sugar and can replace higher-fat proteins like red meat in your rotation. Think of them as a solid neutral choice rather than a therapeutic one. If you’re eating fish three times a week, mixing in one serving of white fish alongside two servings of oily fish is a reasonable approach.
Shellfish: A Mixed Picture
Shrimp, crab, and lobster are low in calories and high in protein, but research on shellfish and diabetes is less encouraging. One study published in Diabetes Care found that regular shellfish consumption was associated with higher dietary cholesterol intake and modestly higher serum cholesterol. After adjusting for cholesterol levels, the link between shellfish and increased diabetes risk weakened, suggesting that the cholesterol content may be part of the problem. Shellfish in moderation is fine, but it shouldn’t be your primary fish choice if you’re focused on managing diabetes.
How You Cook It Matters
Frying fish can erase its benefits. A prospective study of Swedish men found that eating fried fish six or more times per month was associated with a 14% higher incidence of type 2 diabetes compared to eating it once a month or less. Each additional weekly serving of fried fish raised the risk by about 7%. Frying creates compounds called advanced glycation end products, alters the fatty acid profile of the fish, and adds calories from oil and batter.
Baking, grilling, broiling, poaching, and steaming all preserve the omega-3 content without adding harmful byproducts. If you’re eating fish specifically for its diabetes benefits, preparation method isn’t a minor detail. It can determine whether the meal helps or works against you.
How Much to Eat Each Week
Federal dietary guidelines recommend at least 8 ounces of seafood per week, which works out to about two servings. A serving is roughly the size of your palm, or about 4 ounces. For people with diabetes, the cardiovascular data points to two to three servings per week as optimal. A meta-analysis of nine cohort studies covering over 57,000 diabetic patients found that those who ate the most fish had a 14% lower risk of dying from any cause and a 39% lower risk of coronary heart disease compared to those who ate the least. The benefit plateaued at about two to three servings per week, with no additional advantage from eating more.
That cardiovascular connection is especially important for people with diabetes, who face roughly double the risk of heart disease compared to the general population.
Whole Fish vs. Fish Oil Supplements
Eating actual fish appears to be more beneficial than taking supplements, though supplements aren’t useless. Regular fish oil users had a 9% lower risk of developing type 2 diabetes compared to nonusers, and consistent long-term users saw an 18% reduction. But whole oily fish delivered a 22% risk reduction at just two servings per week. Whole fish provides a complete package of protein, selenium, vitamin D, and other nutrients that work alongside omega-3s in ways a capsule can’t replicate.
Keeping Mercury Low
Mercury is the main safety concern with regular fish consumption. The fish highest in omega-3s also tend to be among the lowest in mercury, which makes the choice straightforward. Salmon, sardines, herring, anchovies, trout, and canned light tuna all fall into the low-mercury category. Fish to limit or avoid include shark, swordfish, tilefish, king mackerel, and bigeye tuna, all of which accumulate more mercury due to their size and position in the food chain. Sticking to the recommended two to three servings per week from the low-mercury list keeps your exposure well within safe limits.