Advancing the Value of Carb Counting

We can now take a look at more specific concepts beyond the amount of carbohydrates consumed. Some carbohydrates may be more easily and quickly absorbed than others. Some carbohydrates may act more like fibers than sugars. While the amount of carbohydrates consumed at a sitting is a higher priority than the type consumed in most cases, it may help to know a bit more about which types of carbohydrates and foods may reduce or increase the risk for hyper- or hypoglycemia.

You may have heard of this concept as “glycemic index” and “glycemic load”. (3) Glycemic index (GI) classifies foods according to how fast and how high they raise blood sugar levels after they are consumed. A high number means that the food may raise blood sugar significantly or quickly and a low number means that the food is more slowly absorbed, flattening the curve as it relates to blood sugar increases. The scale goes from 0-100, with a 100 score representing glucose. Simple sugars tend to have a higher score while foods with fat and soluble fibers tend to have a lower score. So, you can imagine that simple white bread has a higher score (75), while something with more fiber has a lower score, such as whole grain spaghetti. Cornflakes are rated at about 80 while muesli is rated about 57. Fruits have a combination of some of the sugar that is more slowly absorbed and soluble fiber as in apples (rating of 36) while sugary fruits, such as watermelon, have a higher rating (76). Milk and yogurt tend to have a lower rating (37 and 41) while rice milk has a higher rating (86).

In addition to ratings of individual foods, one has to consider a “glycemic load” or the score that might be seen with a meals--and that likely includes a variety of foods with mixed glycemic ratings. This is where one of the problems arises in using the glycemic index and glycemic load. It tends to be a bit complex and because we don’t typically eat single foods, it may be unreliable. And, it may be difficult to admit that chocolate has a better rating (40) than rice crackers or crisps (87). Still, the concept can help us to decide between food choices we have in front of us. 

All that said, the amount of carbohydrates consumed, regardless of source, has the biggest effect on blood glucose and is the main reason why medical nutrition therapy for prediabetes and diabetes is concentrated on carbohydrate counting.

Medication strategies used to aid blood glucose control may include those that slow gastric emptying and intestinal absorption with the aim to reduce hyperglycemia in response to carbohydrate consumption. We know that there are some constituents in foods that can either delay gastric emptying or slow the absorption of glucose in the small intestine. Fat can delay gastric emptying and may dilute carbohydrates for absorption. (4) An investigation of the effects of soluble fiber (guar gum) and protein (whey protein) suggested that there is an effect on the small intestine’s absorption of glucose and insulin stimulation. (5) The delays in gastric emptying and small intestinal absorption may not change the “area under the curve” as much as it can reduce the initial glycemic response. Still much more research should be done before clear recommendations can be made on the macronutrient mixes (carbs, protein, and fat) to optimize glycemic control.

Because there is a greater risk for the development of co-morbidities and the greater presence of co-morbidities in diabetes, medical nutrition therapy must consider these factors in building an appropriate carbohydrate counting diet. Weight loss for patients who are overweight or obese will have as priorities improving their diabetes management and reducing their risk for other common co-morbidities. In those cases, overlaying a dietary management plan that allows for weight loss may alter best food choices for patients who are counting carbohydrates. In these cases, weight loss may make carbohydrate counting strategies even more effective.

For instance, recommended choices for reducing the risk of cardiovascular diseases will include foods lower in fat, particularly saturated fats and increasing foods higher in soluble fibers. With a relatively common risk for kidney disease, the amount of sodium and protein should also be carefully considered in recommending food choices. Controlling diabetes in itself can reduce risk for these co-morbidities.

Treatment of diabetes will remain a very high priority in the overall care plan. However, management of kidney disease, cardiovascular diseases, and others are sometimes prioritized, especially in acute situations. While this can complicate dietary recommendations and management, integrating these dietary strategies into the overall medical management plan will be important to achieve the best outcomes.