Comparison between RYGB, DS, and VSG effect on glucose homeostasis

Background Our group has reported a high incidence of reactive hypoglycemia following Roux-en-Y gastric bypass (RYGB) with specific interest in postprandial insulin and the ratio of 1- to 2-h serum glucose levels. The purpose of this study is to compare the 6-month response to oral glucose challenge in patients undergoing RYGB, duodenal switch (DS), and vertical sleeve gastrectomy (VSG). Methods Thirty-eight patients meeting the NIH criteria for bariatric surgery who have reached the 6-month postoperative mark are the basis of this report. Preoperatively and at 6 months follow-up, patients underwent blood draw to determine levels of fasting glucose, fasting insulin, HbA1c, C peptide, and 2 h oral liquid glucose challenge test (OGTT). HOMA-IR and 1 to 2 h ratios of glucose and fasting to 1 h ratio of insulin were calculated. Results All patients underwent a successful laparoscopic bariatric procedure (VSG 013, DS 013, and RYGB012). All operations reduced BMI, HgbA1c, fasting glucose, and fasting insulin. HOMA IR and glucose tolerance improved with all procedures. In response to OGTT at 6 months, there was a 20-fold increase in insulin at 1 h in RYGB, which was not seen in DS. At 6 months, 1-h insulin was markedly lower in DS (p<.05), yet HbA1C was also lower in DS (p<.05). This resulted in 1- to 2-h glucose ratio of 1.9 for RYGB, 1.8 for VSG, and 1.3 for DS (p<.05). Conclusions All operations improve insulin sensitivity and decrease HgbA1c. Six-month weight loss was substantial in all groups between 22-29% excess body weight. RYGB results in marked rise in glucose following challenge with corresponding rise in 1-h insulin. VSG has a similar response to RYGB. In comparison, at 6 months following surgery, DS causes a much lower rise in 1-h insulin, with this difference being statistically significant at p<.05. As a result, DS results in a less abrupt reduction in blood glucose. Although 1- h insulin is lower, DS patients had the lowest HbA1C at 6 months (p<.05). We believe that these findings have important implications for the choice of bariatric procedure for both diabetic and non-diabetic patients.