Fish. Fast and easy to prepare, fish is a good source of protein, and a great substitute for higher-fat meats. Also, fatty fish is the best source of omega-3 fatty acids, those remarkable good-for-you fats that help keep the arteries clear. People with diabetes often have high triglycerides and low levels of HDL, the 'good' cholesterol. Omega-3 fatty acids can improve both numbers. Aim to eat fish at least twice a week. Excellent sources of omega-3s are salmon, mackerel, and tuna.