With respect to the current trends in health it is the dietary intake of carbohydrates, sugar, and dairy that are associated with the development of type 2 diabetes.
Carbohydrates and sugar are well recognized as the primary macronutrients responsible for creating a rapid rise in blood glucose after a meal. This rise in blood glucose evokes an equally intensive rise in insulin levels. High insulin levels leads to hypoglycemia, increased hunger, a craving for more carbohydrates, a clinically relevant weight gain, and eventually type 2 diabetes.
To minimize the elevated spikes in blood glucose, restricting intake of carbohydrates and sugar is a must for most individuals. In one experiment, two groups consumed different amounts of carbohydrates but equal amounts vegetables, calories, fat, and fiber. When bread, rice, pasta, and cereals were replaced with meats, eggs, and nuts the group consuming 30% of calories from carbohydrates compared to 55% did experience lower levels of blood glucose after a meal and an improvement in insulin metabolism. Many studies have confirmed that reducing the dietary calorie intake from carbohydrates improves the metabolism of both glucose and insulin.
The glycemic index and glycemic load commonly discussed in many well-written books does represent the quantity and quality of a particular food’s carbohydrate content and is successful at helping individuals lose weight and body fat. Fortunately, since the index and load are dependent on carbohydrate concentrations, an overall carbohydrate restricted diet will automatically tend to have a lower glycemic load and index effect.
In addition to carbohydrates and sugar the consumption of milk has been found to generate excessively high and hidden insulin levels, and does contribute to the development of diabetes.
The glycemic index which is the golden standard for estimating an insulin response was developed for the purpose of ranking foods according to their carbohydrate content and its extent to which it increases blood levels of glucose, not insulin.
The principal foundation for the glycemic index was originally based on two assumptions. First, that only carbohydrates can influence the blood levels of insulin, and second, that glucose levels are proportional to insulin secretion.
However, since the initial introduction of the glycemic index dietary experiments have proven that the secretion of insulin, in response to many foods, is not proportional to blood levels of glucose, nor to a foods’ carbohydrate content. Foods containing no carbohydrates can induce as much insulin secretion from the pancreatic beta-cells as do carbohydrate rich foods. As an illustration, the insulin response of beef and fish is equal to that of brown rice and grains.
Protein rich foods are able to increase insulin levels without increasing glucose levels. Therefore, the glycemic index rating would not be applicable for protein rich foods. Similarly, the addition of fat to carbohydrate rich meals has been shown to increase insulin levels while glucose levels were declining. Thus, insulin secretion is not proportional to glucose levels nor to a carbohydrate content in many foods.
In addition, the glycemic index fails to take into account the concurrent rise in insulin levels stimulated by pathways not involving glucose. The whey portions of milk’s protein is capable of increasing insulin levels independent of any carbohydrate content.
This may explain in part why many patients have reported unexpected hyperglycemic episodes despite their strict adherence to the carbohydrate counting practices of the glycemic index methodologies.
Finally the glycemic index does not permit testing of foods with little or no carbohydrates. Therefore, it cannot provide any guidance, with respect to insulin, for a large majority of commonly eaten foods found in nutrient databases.
Based on the above principals, the body’s secretion of insulin in response to different types of food is of theoretical and clinical significance.
The following chart taken from laboratory experiments confirms that milk products are potent stimulators of insulin, resulting in insulin levels between 1–4 times greater than predictable from the glycemic index.