Mechanisms of action of a carbohydrate-reduced, high-protein diet in reducing the risk of postprandial hypoglycemia after Roux-en-Y gastric bypass surgery

Background: Postprandial hypoglycemia is a risk after Roux-en-Y gastric bypass (RYGB). Objectives: We speculated that a carbohydrate-reduced, highprotein (CRHP) diet might reduce the risk of hypoglycemia and therefore compared the acute effects of a conventionally recommended (CR) diet and CRHP diet [55/30 energy percent (E%) carbohydrate and 15/30 E% protein, respectively] in RYGB patients. Methods: Ten individuals (2 males, 8 females, mean +/- SD age 47 +/- 7 y; stable body mass index 31 +/- 6 kg/m(2); 6 +/- 3 y post-RYGB) with recurrent postprandial hypoglycemia documented by plasma glucose (PG) <= 3.4 mmol/L were examined on 2 d with isoenergetic CRHP or CR diets comprising a breakfast and subsequent lunch meal. Results: Peak PG was significantly reduced on the CRHP diet after breakfast and lunch by 11% and 31% compared with the CR diet. Nadir PG increased significantly on CRHP (by 13% and 9%). Insulin secretion was reduced, and glucagon secretion increased on the CRHP diet after both meals. Glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide secretion were lower after lunch but unaltered after breakfast on CRHP; beta-cell function and insulin clearance were unchanged. Conclusions: The CRHP diet lowered glucose excursions and reduced insulin secretion and incretin hormone responses, but enhanced glucagon responses compared with the CR diet. Taken together, the results may explain the decreased glucose variability and lower risk of postprandial hypoglycemia.