The effects of the dietary glycemic load on type 2 diabetes risk factors during weight loss.
OBJECTIVE
To compare the effects of two calorie-restricted diets that differ in glycemic load (GL) on glucose tolerance and inflammation.


METHODS
Thirty-four healthy overweight adults, ages 24 to 42 years, were randomized to 30% provided calorie-restricted diets with high (HG) or low (LG) glycemic load for 6 months. Outcomes were changes in glucose-insulin dynamics and C-reactive protein (CRP) levels.


RESULTS
Compared with baseline, levels of fasting insulin, homeostasis model assessment of insulin resistance, post-load insulin at 30 minutes, and incremental area-under-the-curve-insulin during the oral glucose tolerance test were significantly lower in both groups at 6 months (p range, 0.01 to 0.05), but after adjustment for baseline values and weight change, there were no differences between the two groups with regard to changes over time in any parameter. The mean percentage change in insulin sensitivity by a frequently sampled intravenous glucose tolerance test was +26% in the HG group and +24% in the LG group (p = 0.83); first-phase acute insulin release was -20% in the HG group and -21% in the LG group (p = 0.77). More participants on the LG diet (14 of 16 subjects) had a decline in serum CRP, compared with those on the HG diet (7 of 16 subjects) (p < 0.05).


CONCLUSIONS
In healthy overweight adults provided with food for 6 months, the dietary GL did not seem to influence chronic adaptations in glucose-insulin dynamics above that associated with weight loss. This finding highlights the importance of absolute weight loss over the dietary macronutrient composition used to achieve weight loss. The finding of greater declines in CRP concentration after consumption of a low-GL diet warrants further investigation.
Pittas
Anastassios G
AG
Division of Endocrinology, Diabetes and Metabolism, Tufts-New England Medical Center, 750 Washington Street, #268, Boston, MA 02111, USA. apittas@tufts-nemc.org
Roberts
Susan B
SB
Das
Sai Krupa
SK
Gilhooly
Cheryl H
CH
Saltzman
Edward
E
Golden
Julie
J
Stark
Paul C
PC
Greenberg
Andrew S
AS
D000328:Adult; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D004038:Diet, Reducing; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000145:classification*; D005260:Female; D005951:Glucose Tolerance Test; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000378:metabolism; D008297:Male; D009765:Obesity / Q000097:blood / Q000178:diet therapy* / Q000378:metabolism; D012307:Risk Factors; D016896:Treatment Outcome; D015431:Weight Loss / Q000502:physiology*
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin; D002097:C-Reactive Protein