The best way for a diabetic person to control blood sugar level to as near normal as possible is to adopt a diabetic diet. This will help prevent or slow down the progress of long term complications such as heart disease, kidney failure, blindness etc.
The diet should include a low intake of saturated fat, trans-fat, salt and sugar. It should include plenty of fresh vegetables and fruits that are rich in nutrients, antioxidants and phyto-chemicals. A moderate amount of lean meat and alcohol is okay.
The real problem however is carbohydrates. It has a direct impact on sugar level in the blood as compared to fats and protein. Some carbohydrates are converted into glucose very quickly and cause blood glucose to rise sharply. Others cause a gradual rise in blood glucose and it is less damaging.
Researchers have developed an index called the Glycemic Index (GI) which states how fast 50 grams of a carbohydrate of a particular food is converted into glucose and enters the bloodstream. Pure glucose has a ranking of 100 and all other carbohydrates are ranked in relationship to it.
Foods with GI values more than 70 are considered to be high while those between 55 and 70 are medium or intermediate. Foods with GI values less than 55 are considered low.
Foods with high GI include bread, starches, bagel, potatoes and all processed food in general. Also in the high GI category are sugar and honey, grain based snacks like corn chips, prepared cereals like corn flakes and certain fruits such as bananas and raisins.
Moderate GI foods include sweet potatoes, yams and whole grain cereals. Low GI foods include certain fruits such as apples, pears and oranges and legumes such as black-eyed peas, kidney beams, lentils and soya beans. Also included are non- starchy vegetables such as asparagus, broccoli, cabbage, celery, lettuce, tomatoes and green pepper. Generally foods that undergo the least amount of processing have low GI.
While the GI shows how fast the food is converted into glucose it does not indicated the amount of carbohydrate in the food. The amount is also very important as it affects blood glucose levels and insulin production. For this researchers have developed the Glycemic Load (GL). It is calculated by multiplying the GI by the actual number of grams of carbohydrate eaten in a meal divided by 100.
A food can have a high GI but low GL. For example carrots have a high GI of 72 but as carrots contain only a very small amount of carbohydrates per serving, the GL is very low. This means you have to eat a large amount of carrots to have any significant effect on your blood sugar. The GL of a food is considered high if its value is 20 or higher. Between 11 and 19 is medium and 10 or less is considered low.
See this table for GI and GL values of typical foods.
The GI and GL are useful for people with diabetes (and pre-diabetes). It guides them to keep blood sugar stable and improve insulin resistance.
As a guide, nature-made carbohydrates contain soluble and insoluble fibers are better than man-made (highly refined) carbohydrates. Products made from grains and tubers which grow above ground are mostly high in GI and GL. And raw foods have a lower GI than cooked food.
The GI and GL rating encourages you to reduce your intake of refined carbohydrates and increase your intake of fresh vegetables and fruits that are low in sugar. However a food is not good or bad just based on its GI and GL values. When you choose food you should also consider the amount of calories, the amount and type of fats, fiber, salt, vitamins and mineral contents plus the quality and quantity of a carbohydrate food.
I would like to conclude with a few words on fats and proteins. Reduce you intake of fatty red meat and highly processed foods with plenty of additives, coloring and preservatives. Reduce also your intake of fried food, fast food, foods rich in saturated fats and high cholesterol food. Instead consume protein from tofu, skinless chicken, fishes such as salmon and tuna, lean meat and turkey.
Finally distribute your intake of carbohydrates thorough the day to keep blood sugar as normal as possible and eat carbohydrates in combination with lean meat, fiber, fates, beans and peas to slow down the absorption of sugar into the blood and to lower the glycemic effect of carbohydrates.