Age and gender exert differential effects on blood lipids in patients after LAGB and LRYGB

Roux-en-Y Gastric Bypass Is More Effective than Sleeve Gastrectomy in Improving Postprandial Glycaemia and Lipaemia in Non-diabetic Morbidly Obese Patients: a Short-term Follow-up Analysis

PURPOSE

We aimed to compare the effects of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on postprandial glucose and lipid metabolism in addition to weight loss and fasting metabolic profile, in non-diabetic patients undergoing bariatric surgery.

METHODS

Seventy-one patients were consecutively recruited and studied preoperatively, 3 and 6 months after surgery. Of these, 28 underwent RYGB (7 males, age 38 ± 9 years, BMI 46.9 ± 5.0 kg/m²), and 43 SG (9 males, age 38 ± 9 years, BMI 50.2 ± 7.0 kg/m²). A semi-liquid mixed meal was consumed, and blood samples were taken before, and every 30 min after meal ingestion up to 180 min postprandially, for measurement of glucose, insulin, and lipids. The overall postprandial response was assessed as area under the concentration-time curve (AUC).

RESULTS

Baseline metabolic parameters were similar between RYGB and SG. Both groups experienced comparable weight loss, and a similar improvement in fasting glucose, insulin, and insulin resistance. Total and LDL cholesterol levels were lower at 6 months after RYGB compared to SG, while there was no difference in HDL cholesterol or triglycerides. Glucose AUC was lower after RYGB compared to SG at both 3 (p = 0.008) and 6 months (p = 0.016), without any difference in postprandial insulin response. Triglyceride AUC was also lower in RYGB vs. SG at 3 and 6 months (p ≤ 0.001).

CONCLUSIONS

RYGB is superior to SG in improving postprandial glycaemia and lipaemia and cholesterol profile 6 months postoperatively in non-diabetic, severely obese patients. These findings imply procedure-specific effects, such as the malabsorptive nature of RYGB, and less likely a different incretin postoperative response.

Autonomic control and bariatric procedures

The sudden improvement of metabolic profile and the remission of type 2 diabetes after bariatric surgery, well before weight loss, raise important new questions regarding glycemic control. Currently, various types of bariatric procedures target type 2 diabetes in obese and non-obese patients. Nevertheless, the origin of the dramatic metabolic improvements, including glucose homeostasis, is poorly understood, and the role of the gastrointestinal (GI) tract remains relatively speculative, as well as why these procedures are variably effective. One neglected explanation is that such interventions disrupt neural networks mediating GI-brain communication and could alter the autonomic output to the visceral organs, including the liver. Incretins, e.g., glucagon-like peptide 1 (GLP-1), have major influence on the central nervous system. Moreover, the level of GLP-1 is observed to significantly increase after bariatric surgery and could be a key factor in the weight-independent, anti-diabetic effect. Therefore, this review will evaluate the effect of GLP-1 on the central nervous system, with emphasis on the cellular effects of GLP-1, and will provide an overview of the autonomic control of the liver.

Impact of restrictive (sleeve gastrectomy) vs hybrid bariatric surgery (Roux-en-Y gastric bypass) on lipid profile

BACKGROUND

Few studies have evaluated the impact of hybrid versus purely restrictive bariatric surgery on lipid profile, with the results being contradictory. The effect of laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) on lipid profile was compared.

METHODS

A nonrandomized prospective cohort study was conducted on severely obese patients undergoing bariatric surgery. Indication for the type of surgical procedure was based on clinical criteria. Patients on lipid-lowering drugs and those that could not be matched for age, sex, and body mass index were excluded. Finally, 51 patients who underwent LSG and 51 undergoing LRYGB completed this study.

RESULTS

During the first year post-surgery, no differences in percentage of excess weight loss and triglyceride reduction were found between groups. After LRYGR, low-density lipoprotein (LDL) cholesterol concentrations fell significantly (125.9 ± 29.3 to 100.3 ± 26.4 mg/dl, p < 0.001), whereas no significant changes were observed in the LSG group (118.6 ± 30.7 to 114.6 ± 33.5 mg/dl, p = 0.220). High-density lipoprotein (HDL) cholesterol increase was significantly greater after LSG (15.4 ± 13.1 mg/dl) compared with LRYGB (9.4 ± 14.0 mg/dl, p = 0.032). Factors independently associated with LDL cholesterol reduction were higher baseline total cholesterol and undergoing LRYGB. A greater increase in HDL cholesterol was associated with LSG, older age, and baseline HDL cholesterol.

CONCLUSIONS

LRYGB produces an overall improvement in lipid profile, with a clear benefit in all lipid fractions. Although LSG does not alter LDL cholesterol levels, its effect on HDL cholesterol is comparable to or greater than that obtained with malabsorptive techniques.