Risk of Metformin-Associated Lactic Acidosis (MALA) in Patients After Gastric Bypass Surgery.

BACKGROUND: Pharmacokinetic data suggest that the risk of metformin-associated lactic acidosis (MALA) may be increased after Roux-en-Y gastric bypass (RYGB) surgery. The aim of this study was to examine the impact of metformin on plasma lactate levels before and after RYGB surgery. METHODS: Retrospective study of plasma lactate levels before and 3 months after RYGB surgery in patients with type 2 diabetes mellitus (T2DM) not using metformin (MET-0, N = 58), on a stable dose (MET-S, N = 138), or on a decreasing dose (MET-D, N = 85) of metformin. RESULTS: Preoperatively, lactate levels were similar in patients on metformin (1.8 ± 0.05 mmol/L) and those not on metformin (1.7 ± 0.08 mmol/L), P = 0.21. Three months postoperatively, lactate levels had decreased in all groups (P < 0.001) to 1.3 ± 0.07 (SE), 1.4 ± 0.05, and 1.2 ± 0.05 mmol/l in MET-0, MET-S, and MET-D, respectively. Lactate levels differed between the groups (P = 0.03), with the lowest level in MET-D. The number of patients with hyperlactatemia (lactate > 2 mmol/l) decreased from 31 to 14%, from 22 to 8.6%, and from 26 to 4.7% in MET-S, MET-0, and MET-D, respectively. CONCLUSION: Mild hyperlactatemia (lactate > 2 mmol/l) is common in morbidly obese patients with T2DM. It is probably related to increase lactate production by adipocytes. Lactate levels decreased after RYGB-induced weight loss, irrespective of the use of metformin. We therefore conclude that there is no need for routinely lowering of the metformin dose after uncomplicated RYGB surgery, as long as normal renal function is preserved.

Inflammatory Bowel Disease Is Not a Contraindication for Bariatric Surgery.

BACKGROUND: Inflammatory bowel diseases (IBD) are listed as a contraindication for bariatric surgery in various guidelines due to a theoretical higher complication risk. Therefore, little is known about safety and efficacy of bariatric surgery in IBD patients. AIM: We assessed the safety and efficacy of bariatric surgery and postoperative quality of life (QoL) in IBD patients. SETTING: The study was conducted in a large peripheral hospital in the Netherlands. METHODS: All IBD patients who underwent bariatric surgery in our facility were included. Complications, mortality, reoperations, and micronutrient deficiencies were analyzed. Weight loss was assessed 6, 12, and 24 months after surgery. Postoperative QoL was assessed using a disease-specific Inflammatory Bowel Disease Questionnaire (IBDQ). RESULTS: Forty-five patients were included in this study, all diagnosed with IBD (16 ulcerative colitis (UC) and 29 Crohn's disease (CD)) prior to bariatric surgery. Bariatric procedures included Roux-en-Y gastric bypass, sleeve gastrectomy, gastric banding, and revisional surgery. There was no mortality in the entire follow-up period and there were no major perioperative complications. Two major complications in two CD patients occurred during follow-up, gastro-enterostomy bleeding and pyelonephritis with secondary pancreatitis. Mean percentage (± SD) of overall excess weight loss (%EWL) and total body weight loss (%TBWL), 12 months after surgery, were 62.9 ± 27.1 and 26.2 ± 10.6%, respectively. Twenty-four months postoperatively, mean overall %EWL and %TBWL were similar for both UC and CD patients and were 62.9 ± 31.0 and 26.6 ± 12.2, respectively. Mean Bariatric Analysis and Reporting Outcome System (BAROS) score was 3.34 ± 2.42. Median total IBDQ score was 170.8 (min. 77; max. 218). Both scores did not differ significantly between UC and CD patients. CONCLUSION: As bariatric procedures appear safe and effective in this CU and CD population, one could question why bariatric surgery is contraindicated in the patients. Nevertheless, close lifelong monitoring to assure safety and a favorable outcome remains essential.

Patients' Preoperative Estimate of Target Weight and Actual Outcome after Bariatric Surgery.

BACKGROUND: Evidence about the impact of psychological factors on weight loss after bariatric surgery is scarce. This study explores whether patients' preoperative estimate of target weight influences actual weight loss for different types of bariatric procedures. METHODS: Patients eligible for bariatric surgery were instructed twice on how to calculate their expected target weight. They were divided into three groups based on their percentage excess weight loss (%EWL) and percentage total body weight loss (%TBWL). Weight loss 12 and 24 months after surgery was analyzed for each group and per type of surgery. RESULTS: Six hundred fifty-six patients participated in this study. Types of surgery performed were the Roux-en-Y gastric bypass (RYGB, 75%), sleeve gastrectomy (SG, 8.1%), REDO-RYGB (12.5%), and laparoscopic adjustable gastric banding (LAGB, 4.4%). Data of 622 and 410 patients were available for analysis at 12 and 24 months, respectively. Surprisingly, 415 patients (63.3%) overestimated their expected weight loss as opposed to our calculation, based on our own historic data. One hundred thirty-four patients (20.4%) estimated their weight loss correctly and 107 patients (16.3%) underestimated their weight loss. There was a significant higher %EWL 12 months after RYGB surgery for patients who overestimated their weight loss compared to those who estimated their weight loss correctly (p = 0.001). After 24 months and for other types of procedures, no statistically significant differences were found between the three groups. CONCLUSION: Despite instructions on how to calculate target weight, the majority of patients overestimated their weight loss. Actual %EWL 12 months after RYGB surgery might be influenced by setting a low target weight.