12. Remission of Impaired Glucose Tolerance (IGT) to Normal Glucose Tolerance (NGT) in Obese Adults with High Protein vs. High Carbohydrate Diet (90-OR)

Abstract

The purpose of this study is to identify a diet that facilitates weight loss and conversion of patients with impaired glucose tolerance (IGT) to normal glucose tolerance (NGT). Specific aim was to determine if a High Protein (HP) or High Carbohydrate (HC) diet is more effective in conversion of IGT obese adults to NGT. 18 obese, pre-diabetic adults were randomized to a HP or HC diet for 6 months (mo) with all food provided. The HP diet consisted of 30% protein, 30% fat, 40% carbohydrates while the HC diet consisted of 15% protein, 30% fat, 55% carbohydrates distributed by percentage of daily kcals derived for each subject. An Oral Glucose Tolerance Test (OGTT) was performed at Baseline (BL) and 6 mo to determine IGT/NGT status. A 2 hr glucose between 140 to 199 mg/dl was considered IGT. DXA was done at BL and 6 mo. Food pick up and weight checks were weekly. Both diet groups had weight loss, improvement in insulin sensitivity determined by HOMA IR [HP (BL 4.69 ± 0.26; 6 mo 1.58 ± 0.14)], [HC (4.62 ± 0.26; 6 mo 3.15 ± 0.27)] and decrease in HbA1c [HP (BL 5.99 ± .05; 6 mo 5.53 ± .02)], [HC (BL 5.9 ± .04; 6 mo 5.69 ± .06)]. The HP diet had a 100% (9/9) conversion rate to NGT while the HC diet had a 44.4% (4/9) conversion rate. HP group had a 2.8 ± .4% increase in lean body mass and 2.5 ± 0.4% decrease in fat mass while the HC group had a 2.1 ± 1.1% and 3.5 ± 0.9 % decrease in lean and fat mass with greater overall average weight loss. Both diets resulted in improvement in glucose tolerance and insulin sensitivity but the HP diet was most effective. Our results suggest that lean body mass preservation may be more important than total weight loss in the conversion of IGT to NGT, possibly due to the high insulin sensitivity of muscle cells.