Sardines are one of the best fish choices for people with diabetes. They contain zero carbohydrates, meaning they have no direct impact on blood sugar levels. A standard 3.75-ounce can of sardines in oil delivers 22.6 grams of protein along with omega-3 fatty acids, calcium, and vitamin D, all of which play roles in metabolic health.
Why Sardines Work Well for Blood Sugar
The most important number for anyone managing diabetes: sardines contain 0 grams of carbohydrates per serving. Since carbohydrates are what raise blood sugar after a meal, sardines won’t cause a glucose spike on their own. That makes them a reliable protein source you can build meals around without complicated carb counting.
Protein also helps slow the absorption of carbohydrates from other foods on your plate. Pairing sardines with whole grains, vegetables, or legumes can blunt the post-meal blood sugar rise you’d get from eating those carbs alone. The Diabetes Plate Method recommends filling a quarter of your plate with lean protein, and sardines fit that role well.
What a Clinical Trial Found
A randomized controlled trial from the Universitat Pompeu Fabra in Barcelona tested sardines specifically in people at risk for type 2 diabetes. Researchers recruited 152 adults aged 65 and older who had elevated fasting blood sugar. Both groups received the same dietary counseling for diabetes prevention, but one group added 200 grams of sardines (about two cans) per week for a full year.
The sardine group saw meaningful improvements across several markers. They had lower insulin resistance scores, higher levels of HDL (the protective cholesterol), lower triglycerides, and reduced blood pressure. Significantly fewer people in the sardine group remained classified as “very high risk” for developing type 2 diabetes compared to the control group. The researchers noted that the protective effect likely comes from the combination of nutrients working together: omega-3 fats, taurine, calcium, and vitamin D, rather than any single ingredient.
How Much to Eat Per Week
Both the American Diabetes Association and the American Heart Association recommend at least two servings of fish per week. One can of sardines counts as a serving, so eating sardines twice a week puts you right in line with those guidelines. The Barcelona study used a similar amount (200 grams per week) and saw results over 12 months, suggesting this is a reasonable and sustainable target.
Choosing the Right Can
Canned sardines come packed in water, olive oil, or tomato sauce, and the differences matter more for calories than for sodium. Sardines in water contain about 270 mg of sodium per serving, while sardines in oil come in at roughly 280 mg. That’s a negligible difference. If you’re watching sodium intake because of high blood pressure (common alongside diabetes), either option is moderate, but check labels since brands vary.
Sardines packed in olive oil are higher in calories due to the added fat, though olive oil itself is a heart-healthy choice. If you’re managing weight as part of your diabetes plan, sardines in water are the leaner option. Draining the liquid before eating reduces both sodium and excess fat regardless of packing type.
Very Low Mercury Levels
Sardines are among the safest fish when it comes to mercury contamination. FDA testing found sardines contain an average of just 0.013 parts per million of mercury. For comparison, canned albacore tuna averages 0.350 ppm (about 27 times higher), and swordfish averages 0.995 ppm (about 77 times higher). Because sardines are small and low on the food chain, they don’t accumulate heavy metals the way larger predatory fish do. This makes them safe to eat multiple times per week without concern.
One Consideration: Gout Risk
Sardines are classified as a high-purine food. Purines break down into uric acid in the body, and excess uric acid can trigger gout flares. This matters for people with diabetes because the two conditions frequently overlap. According to the Mayo Clinic, sardines, anchovies, and shellfish are among the seafood types highest in purines.
If you have both diabetes and gout, you don’t necessarily have to avoid sardines entirely. Small portions can still fit into a gout-friendly diet. But if you experience frequent gout attacks, it’s worth being cautious about how often sardines appear on your plate and choosing lower-purine fish like salmon or tilapia on some days instead.
Simple Ways to Add Sardines to Meals
- On whole-grain toast with a squeeze of lemon and sliced avocado, giving you protein, healthy fats, and fiber in one meal.
- Tossed into salads as a swap for croutons or processed deli meat, adding protein without extra carbohydrates.
- Mixed into pasta sauce where they dissolve into the tomato base and add richness without a strong fishy taste.
- Mashed with Greek yogurt and herbs as a high-protein dip for raw vegetables.
Eating the bones (which are soft in canned sardines) is encouraged. They’re a significant source of calcium and vitamin D, both nutrients that appear to contribute to the metabolic benefits seen in research.