Carb Management

Carbohydrates and Diabetes

People with diabetes must pay close attention to their dietary intake, including portion sizes, meal frequency, and carbohydrates. The carbohydrates (or carbs) in the food you eat are the body’s primary source of glucose. Carbs convert into glucose in the blood, which is used as fuel by all the cells in the body. Foods high in dietary carbohydrates include sugar, starchy foods like potatoes, corn, and pasta, and grain-based foods like breads and cereals. Carbohydrates are also found in dairy products and all fruits and vegetables.

Diabetes does not mean that these carbohydrate-containing foods must be completely cut out of the diet; in fact, many contain nutrients essential to good health. However, intake must be carefully controlled and other blood glucose lowering tools such as exercise should be used to balance out their effects. For most people, special treats such as a slice of birthday cake can be an occasional indulgence, as long as portions are controlled and they’re figured into the overall daily carbohydrate and calorie allowance.

Careful postprandial (after-meal) blood sugar testing and logging is an excellent tool for understanding the impact of new foods on blood glucose levels. Using this information and working with your diabetes care team is the best way to determine your optimal daily carb intake.

Other Food Factors

Other nutrients in a meal — including fiber, fat, and protein — can also make a big difference in how carbs affect blood sugar levels. Pizza is a good example. It’s infamous for causing a delayed blood glucose rise in people with diabetes. This is because the high fat content slows the absorption of carbohydrates in the intestines. And fiber, although considered a carbohydrate, usually causes less dramatic rise in blood glucose levels because it isn’t absorbed in the gastrointestinal tract.

Not All Carbs are Created Equal

To complicate things further, certain foods can cause a more dramatic blood glucose rise than others, even though they may have an equivalent amount of carbohydrates, gram-for-gram. This is attributable to the glycemic index (GI) or glycemic load (GL) of a food — those foods with a high glycemic impact will cause blood glucose to rise higher and faster than foods with a lower one. Finally, it’s important to realize that metabolic reactions to foods are highly individual, and a meal that sends one person’s blood sugars sky-high may barely cause a blip for another. Home blood sugar testing is the best way to discover your own particular response pattern.

Reviewed by Susan Weiner, R.D., M.S., C.D.E., C.D.N. 3/08