Blood glucose response to rate of consumption of digestible carbohydrate.

When the glycemic response to consuming digestible carbohydrate is measured, little or no attention appears to have been paid to the possible effect on this response of the rate at which the food is consumed. We compared glycemic responses when volunteers ate or drank foods containing digestible carbohydrate as rapidly as possible, or in five equal portions over 12 min. Expecting that the response would be greater when the food was consumed rapidly, we found that the responses were equally and randomly distributed between the two rates of eating.

The glycemic response is a personal attribute.

The Glycemic Index (GI) is a measure of the extent of the change in blood glucose content (glycemic response) following consumption of digestible carbohydrate, relative to a standard such as glucose. We have explored whether the reported GIs of foods are a sufficient guide to a person wishing to avoid large glycemic responses and thereby avoid hyperglycemia. For this purpose, volunteers carried out multiple tests of four foods, following overnight fasting, measuring the glycemic response over 2 H.

Protein causes a glycemic response.

The glycemic index is used to compare the extent to which the blood glucose level increases following the consumption of foods containing digestible carbohydrate and is considered to be zero, or not measurable, if the food, such as protein, is carbohydrate-free. We have found that after overnight fasting, the consumption of several varieties of meat caused significant increases in blood glucose levels. We consider these possibly to be because of gluconeogenesis from the digested protein.

Why the linkage of glycogen to glycogenin was so difficult to determine.

Glycogenin is the self-glucosylating enzyme that primes mammalian and yeast glycogen synthesis. It proved to be the long-suspected, covalently bound protein component of glycogen. One of the most difficult aspects in elucidating the role of glycogenin was to learn the nature of its covalent bond to glycogen.

Glycogenin: the primer for mammalian and yeast glycogen synthesis.

Glycogen synthesis, whether in mammalian tissue, yeast, or Agrobacterium tumefaciens or other bacteria, is initiated by autoglucosylation of a protein. Initiation in muscle, by a self-glucosylating protein, glycogenin-1, is the most thoroughly studied system, as is described here. These relatively recent findings have prompted a rekindling of interest in the intermediates lying between the primer and mature mammalian glycogen.