Carbohydrates, protein and fat are the macro nutrients that provide your body with energy. Of these three, carbohydrates have the greatest effect on your blood sugar by far. This is because they are broken down into sugar, or glucose, and absorbed into your bloodstream.
Carbohydrates include starches, sugar and fiber. However, fiber isn't digested and absorbed by your body in the same way other carbs are, so it doesn't raise your blood sugar. Subtracting fiber from the total carbs in a food will give you its digestible or "net" carb content. For instance, if a cup of mixed vegetables contains 10 grams of carbs and 4 grams of fiber, its net carb count is 6 grams.
When people with diabetes consume too many carbohydrates at a time, their blood sugar levels can rise to dangerously high levels. Over time, high levels can damage your body's nerves and blood vessels, which may set the stage for heart disease, kidney disease and other serious health conditions. Maintaining a low carb intake can help prevent blood sugar spikes and greatly reduce the risk of diabetes complications.