Potatoes, sweet potatoes, taro and yam belong to this type of food stuff. The carbohydrate content of raw potatoes is absorbed slowly, but boiling causes the cell walls to burst. This allows the carbohydrates to be absorbed more quickly from the intestines. The carbohydrate content of mashed potatoes is absorbed as quickly as pure glucose. This can give a quick rise in blood glucose after the meal but may also result in hypoglycaemia 2-3 hours later, since all the carbohydrates in the mashed potatoes will have been absorbed during a fairly short time after the meal. If you change the surface of a potato (for example, by frying, deep frying, or storing it in the refrigerator) the glucose will be absorbed more slowly than if you eat it freshly boiled. The manufacturing process and the high fat content of potato crisps cause the glucose contained in these to be absorbed very slowly.
In one study of adults, chocolate cake was substituted for a baked potato without an increase in blood glucose levels. If the chocolate cake was added to the baked potato, the glucose level increased. However, remember that chocolate cake and baked potato are very different in nutritional and energy value!
At one time, people with diabetes were strongly advised to eat unsweetened bread. Today, we know that white bread raises the blood glucose level every bit as rapidly as ordinary sugar. However, margarine and something with a high fat content (e.g. cheese) on the bread will slow the rise in blood glucose by delaying emptying of the stomach. Bread (such as whole grain) that is high in fibre will also slow down any rise in blood glucose levels.
If you bake your own bread, it is perfectly acceptable to use an ordinary recipe. It should not be necessary to leave out sugar or experiment with alternative sweetening agents. Three to 6 tablespoons (45-90 ml) of sugar or syrup for dough made from 0.5 litre (1 pint) of liquid can be used as only a small amount will remain in the bread after baking. It is more important to choose bread that is rich in fibre rather than omitting small amounts of sugar.
Gluten-free wheat bread gives a quicker rise in blood glucose compared with the same amount of bread containing gluten.
Nutritious meals do not always need to be hot. A sandwich or roll with tuna, egg, lean meat, chicken or cheese and salad, along with yogurt, fromage frais or fruit can be very enjoyable.
Unsweetened breakfast corn cereal (corn flakes) contains 90% starch, most of which rapidly becomes available as glucose. Sweetened (sugar-frosted) flaked corn cereal, on the other hand, contains around 50% starch and 50% sugar. Initially, both give the same blood glucose rise but sweetened corn flakes give slightly lower blood glucose levels after 3 hours. This may surprise you, but corn starch raises the blood glucose faster than ordinary sugar. The volume of sweetened corn cereal is around 25% less for the same carbohydrate content, so pre-sweetened corn cereals can be used in a meal plan without increasing the blood glucose if the total amount of carbohydrate is taken into consideration when estimating the insulin dose. However, increasing the number of calories you consume will cause you to put on weight in time.
Pasta gives a slow rise in blood glucose since it is prepared from crushed or cracked wheat, not wheat flour, which causes the starch to be enclosed within a structure of protein (gluten).This makes pasta a suitable food for people with diabetes. It has the additional advantage of being popular with children. If you are using rapid-acting insulin (Humalog), however, the rise may even be too slow, resulting in hypoglycaemia within 30-60 minutes. If this applies to you, you should take your NovoRapid or Humalog after your meal, or use regular short-acting insulin when eating pasta (or beans as in chilli con carne). If you have a pump, you can use a prolonged bolus dose.
Thinner pasta, such as macaroni, gives a quicker blood glucose response than spaghetti. Cooking time is not a factor in how quickly the blood glucose is raised by spaghetti except in extreme cases of overcooking. Tinned spaghetti increases the blood glucose just as quickly as white bread. As the gluten content of pasta contributes to the slow rise in blood glucose, gluten-free pasta allows blood glu-cose levels to rise faster.
Pizza contains bread, cheese, meat or fish, and possibly vegetables. In other words, it is a balanced meal. One problem if you have diabetes is that a pizza meal will usually contain more bread than a traditional meal. The bread is baked hard which causes the carbohydrates to be absorbed more slowly. Cheese has a high fat content, which causes the stomach to empty more slowly. Try taking 1-2 extra units of insulin (or according to the actual carbohydrate content if you have calculated this) with the pizza or avoid eating the crust. If you use rapid-acting insulin (NovoRapid, Humalog, Apidra), it may be better to take this after the meal or substitute a dose of short-acting insulin (Actrapid, Humulin S, Insuman Rapid) instead. If you have a pump you can use an extended bolus dose.