High blood sugars caused by type 2 diabetes can damage the blood vessels and nerves that support kidney function, leading to chronic kidney disease and renal failure. To preserve as much kidney function as possible, follow a low-sodium diet that lowers blood pressure and stabilizes blood sugar. In addition to limiting carbohydrates, a diabetic renal diet may also limit protein, fluid and electrolyte consumption.
The Renal Diet
Up to 40 percent of people with type 2 diabetes develop kidney disease, according to Harvard's Joslin Diabetes Center. Your kidneys filter waste from your body; the first principle of any renal diet is to give your kidneys less work to do -- by filtering what food goes into your body. Your kidneys have to work hard to process protein, so most renal diets limit protein consumption to between 4 and 6 oz. daily. Fluids are restricted, as are electrolytes such as sodium, potassium and phosphorus. If your kidneys can't excrete excess phosphorus, it can leach calcium from your bones. Excess potassium can cause a dangerous irregular heartbeat, and excess sodium may lead to high blood pressure, water retention and swelling.
Carbohydrate Intake
Most diabetics limit carb consumption and try to choose low-glycemic-index (low-GI) carbs that have little impact on glucose levels. When following a renal diet, you don't need to eliminate any more carbs than your current diabetes treatment plan calls for -- you'll just need to choose low-GI carbs that are also low in potassium and phosphorus. Avoid fruits and vegetables high in potassium and phosphorus, such as tropical fruits, oranges, pomegranates, kumquats, artichokes, okra, spinach, tomatoes and pumpkin. Because whole grains are higher in minerals than refined grains, you may need to eat white bread and white rice rather than whole grain bread and brown rice. The lack of fiber in refined grains might raise your blood sugar more than high-fiber choices -- you'll need to compensate by eating less, exercising more or increasing your insulin dosage.
Protein and Fat Intake
Cutting protein consumption may leave you with fewer calories than your body needs. Since eating more carbohydrates will elevate your blood sugar level, you may need to add calories from fat. Choose heart-healthy unsaturated fats such as olive and canola oil. Avoid saturated fats such as butter, and use margarine instead. When eating protein, choose nutrient-dense high-quality protein, such as fish, seafood, poultry and eggs. Choose fresh foods, not processed meats like cold cuts or hot dogs, which are high in sodium.
Beverages
Although diet soda may be acceptable for diabetics, renal patients must limit fluid intake and avoid phosphoric acid, found in many brown colas. It's also important to avoid sports drinks that contain added electrolytes. Alcohol has an immediate impact on blood sugar and on your kidneys, which have to work very hard to filter any type of alcohol, but most especially beer. Use non-dairy creamer and milk substitutes, such as rice milk, to avoid the potassium and phosphorus in most dairy products. Try drinking water, seltzer with a splash of juice for flavor, tea and coffee. When limiting your fluids, remember that watery foods, such as soup and jello, count toward your total fluid intake. Even ice has to be taken into account.
