Glycemic Index Key Determinant of Blood Glucose Profile in Non-Diabetic Individuals?

Glycemic Index (GI) refers to comparable ease with which a given carbohydrate load appears in the circulation – this index varies considerably between various sources of carbohydrate and is a function of the ease with which this carbohydrate is digested into and absorbed (as glucose) into the blood stream.

But how important the GI of foods, especially when meals are not consumed in a highly controlled research setting, in determining glucose profiles remains an area of debate.

In a study, just published in the Journal of Nutrition, we looked at the relationship between the GI of a self-selected breakfast consumed in ‘free-living’ individuals by studying their glycemic response for two hours after breakfast using continuous glucose monitoring.

We studied 57 non diabetic overweight and obese adults with a mean BMI of about 34 and mean waist circumference of 109, who underwent a 75-g oral glucose tolerance test (OGTT) and, on a separate day, wore a continuous glucose-monitoring system (CGMS) for 24 h during which time they recorded all foods consumed.

The protein, fat, and available carbohydrate (avCHO) content and GI of the breakfast meals were calculated from the food records and the incremental areas under the glycemic response curves (iAUC) for 2 h after breakfast (iAUC(breakfast)) were calculated from CGMS data.

The measured variables accounted for almost 60% of the total variation in glycemic response, with the GI explaining by far the greatest proportion of this variation (30%). The response to the OGTT and avCHO explained an addition 11% each with waist circumference explaining a further 3%.

The effects of fat, protein, dietary fiber, age, sex, and BMI were not significant determinants of glycemic response.

Our study thus shows that the GI is a significant and more important determinant of individual glycemic responses elicited by self-selected breakfast meals, than just the intake of carbohydrates.

These findings certainly support the notion that one should perhaps look beyond simply the grams of sugar or carbohydrates in your diet to determine the actual glycemic risk of foods.

Edmonton, Alberta

Kochan AM, Wolever TM, Chetty VT, Anand SS, Gerstein HC, & Sharma AM (2011). Glycemic Index Predicts Individual Glucose Responses after Self-Selected Breakfasts in Free-Living, Abdominally Obese Adults. The Journal of nutrition PMID: 22090469