You need to be particularly careful with saturated fat and so called "trans fats". Foods that contain large amounts of saturated fats include dairy products and red meats. They are also found in many snack foods such as chocolate, cakes and pastries and sometimes in crisps. Trans fats are often listed as "partially hydrogenated vegetable oil" or "vegetable shortening" on the food label.
Try to use monounsaturated and polyunsaturated fats where possible instead. An increased intake of monounsaturated fats may even improve your HbA1c. The softer the fat the better. Liquid margarine and oil do not contain any trans fats at all and also have a low content of saturated fatty acids. Be careful of palm, vegetable and coconut oil as all are high in saturated fat and used widely in different products.
Today, dietitians promote monounsaturated fats (MUFA) which have a protective effect against heart disease. Choose a margarine that contains monounsaturated fat. Light margarine is not recommended for very young children, however, as they have an increased need for fat in their diet. Ordinary margarine and butter contain only 3% polyunsaturated fat. Olive oil and rapeseed oil contain large amounts of monounsaturated fat and are useful for frying. However, if the frying pan is very hot, the unsaturated fat can be broken down. Sunflower oil is an example of oil, which is good for frying as it is not broken down as readily as olive oil. Up to the age of 5 years, it is expected that the proportion of energy derived from dietary fats will fall from about 50% (as it is in breast milk and infant formula) to levels recommended for adults, but this moderation should not occur below the age of 2 years. Below this age the energy density of foods is important, and also low fat foods in toddlers may be associated with rapid gastric emptying and diarrhoea.
Many people believe that fat increases the blood glucose level since people with diabetes are usually advised to cut down on fat in their diet. However, fatty food has no direct effect on the blood glucose level. Fat affects the blood glucose level indirectly by slowing the rate at which the stomach empties. Studies on monkeys have found that their stomachs empty portions of food through the lower sphincter with the same amount of energy every minute. As fat yields more energy than carbohydrate, the stomach is emptied more slowly when the fat content is high. A meal with a high fat content, therefore, will cause the blood glucose level to rise more slowly. The fat in food must pass into the intestine before it can affect the emptying rate of the stomach. This means that if you start a meal with something rich in fat, the signal that slows down the emptying rate will reach the stomach more quickly. If you eat a meal very rich in fat, you may still have food remaining in your stomach when you are about to have your next meal. If you are using multiple injections, you will need to decrease the amount of food you plan to eat (without changing the insulin dose), if you are to avoid an increase in blood glucose. If you are using rapid-acting insulin you may be at risk of hypoglycaemia shortly after a meal rich in fat. If so, try giving yourself the injection after the meal instead of before.
It is the total amount of fat over time that is important in the long run. You can cut down on fat during the week and then have a festive meal at the weekend, complete with a delicious cream sauce, or a takeaway meal. Most fat substitutes, for example maltodextrin (modified food starch), are made of carbohydrate, which may affect your blood glucose.