Your body uses potassium in digestion, metabolism, regulating muscle tissue and homeostasis -- balancing the chemical and electrical processes in your body. Excess potassium can lead to loss of muscle and nerve control, an irregular heart beat and cardiac arrest. Your kidneys remove excess potassium from your bloodstream, but when you have renal disease, commonly caused by diabetes, your kidney's aren't able to work properly. A potassium build-up, called hyperkalemia, occurs -- which might have fatal consequences. Prevention of hyperkalemia is the best treatment, and following a low-potassium diet can help.
Choose carbohydrates that are low in potassium and sugar. Carbohydrates have a direct impact on blood sugar, and most diabetics count carbs carefully. Unfortunately, high-fiber low-glycemic index carbs that are often recommended for people with diabetes can be high in potassium and phosphorous. Instead of eating two slices of whole grain bread, you may have to eat just one slice of white bread as one serving of a low-potassium carb.
Avoid processed proteins. Cold cuts, lunch meats, sausages and meats cured with nitrates tend to be higher in potassium than lean cuts of meat, fish, seafood, poultry and eggs. You'll also want to limit nuts and dried legumes. Use low-fat dairy products in moderation. Talk to your doctor about protein consumption. People with renal failure often need to follow a low-protein diet, if they haven't started dialysis. Dialysis patients often require more protein, due to tissue loss.
Learn which fruits and vegetables are better choices on your renal diabetes diet. You may have been avoiding starchy vegetables because of their high carbohydrate content; but broccoli, tomatoes, artichokes, okra and spinach should also be avoided if you have kidney disease. Choose fruits such as apples, berries and grapefruit, but limit cantaloupe, bananas, oranges, nectarines, pears and papaya. You can't judge how much potassium is in a food just by looking at, so you may need a renal diet guide that lists the electrolyte content of food.
Pay attention to portion control -- if you eat three servings of a low-potassium food, you may be consuming too much potassium. Cook your foods at home. The more you eat at restaurants, the less control you have over food preparation, sodium and fat content and portion control.
If you have any symptoms of hyperkalemia, such as weak heartbeat, shortness of breath, fainting, nausea or weakness, seek immediate medical attention.