Which Fish Should People with Diabetes Avoid?

People with diabetes should avoid high-fat fish, high-mercury fish, processed fish, high-purine fish, and fish that cause allergic reactions, as these may adversely affect their condition and interfere with daily life and work.

High-fat fish: such as mackerel. Although rich in omega‑3 fatty acids, it has a high fat content. Excessive intake of high-fat foods may raise blood lipid levels and increase the risk of cardiovascular disease. Since cardiovascular disease is one of the common complications of diabetes, intake of high-fat fish should be limited.
High-mercury fish: such as swordfish and marlin, which may contain high levels of mercury. Mercury is a toxic heavy metal; long-term intake may harm the nervous system, leading to decreased cognitive function and memory loss. Protecting neurological function is especially important for people with diabetes, so high-mercury fish should be avoided.
Processed fish: such as smoked fish, salted fish, and canned fish, which often contain high levels of salt and additives. A high-sodium diet may raise blood pressure and increase cardiovascular risk. Additives in processed fish may also negatively affect blood glucose control and cause glucose fluctuations.
High-purine fish: such as anchovies, which are high in purines. Purines metabolize into uric acid in the body; excessive intake may lead to hyperuricemia and increase the risk of gout. Hyperuricemia in diabetic patients may increase the burden on the kidneys and impair renal function.
Allergenic fish: such as pomfret, which may trigger allergic reactions. People with diabetes often have a sensitive immune system. Eating allergenic fish may cause symptoms such as skin itching, difficulty breathing, and gastrointestinal discomfort. Severe allergic reactions can be life-threatening. Patients should check their allergy history before eating fish and avoid any species that may cause an allergic response.

Patients are advised to choose fish that are low in fat, low in mercury, fresh, low in purines, and low in allergenic risk, such as cod and sea bass, to maintain stable blood glucose and overall health. Maintaining a varied diet, regularly monitoring blood glucose and lipid levels, and following medical guidance in daily life will help improve diabetes management and quality of life.