Metabolic improvements following Roux-en-Y surgery assessed by solid meal test in subjects with short duration type 2 diabetes

Abstract

Background: Glucose homeostasis improves within days following Roux-en-Y gastric bypass (RYGB) surgery. The dynamic metabolic response to caloric intake following RYGB has been assessed using liquid mixed meal tolerance tests (MMTT). Few studies have evaluated the glycemic and hormonal response to a solid mixed meal in subjects with diabetes prior to, and within the first month following RYGB.

Methods: Seventeen women with type 2 diabetes of less than 5 years duration participated. Fasting measures of glucose homeostasis, lipids and gut hormones were obtained pre- and post-surgery. MMTT utilizing a solid 4 oz chocolate pudding performed pre-, 2 and 4 weeks post-surgery. Metabolic response to 4 and 2 oz MMTT assessed in five diabetic subjects not undergoing surgery.

Results: Significant reductions in fasting glucose and insulin at 3 days, and in fasting betatrophin, triglycerides and total cholesterol at 2 weeks post-surgery. Hepatic insulin clearance was greater at 3 days post-surgery. Subjects exhibited less hunger and greater feelings of fullness and satisfaction during the MMTT while consuming 52.9 ± 6.5% and 51.0 ± 6.5% of the meal at 2 and 4 weeks post-surgery respectively. At 2 weeks post-surgery, glucose and insulin response to MMTT were improved, with greater GLP-1 and PYY secretion. Improved response to solid MMTT not replicated by consumption of smaller pudding volume in diabetic non-surgical subjects.

Conclusions: With a test meal of size and composition representative of the routine diet of post-RYGB subjects, improved glycemic and gut hormone responses occur which cannot be replicated by reducing the size of the MMTT in diabetic subjects not undergoing surgery.

Trial registration: Clinical Trials.gov Identifier: NCT00957957 August 11, 2009.

Keywords: C-peptide; GLP-1; Glucose; Gut hormones; Insulin; Meal test; Roux-en-Y.

Fig. 1

Hunger and satiety ratings during the pre- and post-surgery solid meal test. Pre-surgery AUC_total for each measure significantly different (P < 0.05) from that at 2 and 4 weeks post-surgery. See Table 2

Fig. 2

Glycemic and hormonal response to solid meal test is improved following RYGB surgery. Pre-surgery AUC_total for glucose, insulin and active GLP-1 significantly different (P < 0.05) from that at 2 and 4 weeks post-surgery. See Table 3

Fig. 3

Reductions in meal size do not normalize the glycemic and hormonal response to caloric challenge in subjects with type 2 diabetes. Glucose AUC_total following consumption of 2 oz of pudding lower than after 4 oz (P = 0.016). Insulin and C-peptide AUC_total not significantly different by pudding size