Bariatric surgery is the most effective treatment for patients with morbid obesity. Until recently, Roux-en-Y gastric bypass was regarded as the standard bariatric procedure. However, sleeve gastrectomy is being performed with increasing frequency despite the lack of evidence regarding its long-term efficacy.¹ The sleeve gastrectomy procedure is technically easier, faster to perform, and potentially safer compared with Roux-en-Y gastric bypass. However, much more data on clinical and metabolic long-term outcomes are available on the Roux-en-Y gastric bypass procedure. Early and midterm results of sleeve gastrectomy showed potential benefit, but only a limited number of randomized studies have compared outcomes of sleeve gastrectomy and Roux-en-Y gastric bypass head to head, most of which were underpowered because of low patient numbers, short follow-up, or both.^2-6

The exclusion of the proximal small intestine is thought to play a major role in the rapid improvement in the metabolic control of diabetes after gastric bypass. In this randomized, prospective, parallel group study, we sought to evaluate and compare the effects of laparoscopic Roux-en-Y gastric bypass (LRYGB) with those of laparoscopic sleeve gastrectomy (LSG) on fasting, and meal-stimulated insulin, glucose, and glucagon-like peptide-1 (GLP-1) levels. Thirteen patients were randomized to LRYGB and 14 patients to LSG. The mostly nondiabetic patients were evaluated before, and 1 week and 3 months after surgery. A standard test meal was given after an overnight fast, and blood samples were collected before and after food intake in both groups for insulin, GLP-1, glucose, PYY, and ghrelin concentrations. This trial was registered in www.clinicaltrials.gov (NCT00356213) before the first patient was randomized. Body weight and body mass index decreased markedly (P < 0.002) and comparably after either procedure. Excess BMI loss was similar at 3 months (43.3 ± 12.1% vs. 39.4 ± 9.4%, P > 0.36). After surgery, patients had markedly increased postprandial plasma insulin and GLP-1 levels, respectively (P < 0.01) after both of these surgical procedures, which favor improved glucose homeostasis. Compared with LSG, LRYGB patients had early and augmented insulin responses as early as 1-week postoperative; potentially mediating improved early glycemic control. After 3 months, no significant difference was observed with respect to insulin and GLP-1 secretion between the 2 procedures. Both procedures markedly improved glucose homeostasis: insulin, GLP-1, and PYY levels increased similarly after either procedure. Our results do not support the idea that the proximal small intestine mediates the improvement in glucose homeostasis.

Laparoscopic sleeve gastrectomy (LSG) is performed almost as often in Europe as laparoscopic Roux-Y-Gastric Bypass (LRYGB). We present the 3-year interim results of the 5-year prospective, randomized trial comparing the 2 procedures (Swiss Multicentre Bypass Or Sleeve Study; SM-BOSS). Initially, 217 patients (LSG, n = 107; LRYGB, n = 110) were randomized to receive either LSG or LRYGB at 4 bariatric centers in Switzerland. Mean body mass index of all patients was 44 ± 11 kg/m, mean age was 43 ± 5.3 years, and 72% of patients were female. Minimal follow-up was 3 years with a rate of 97%. Both groups were compared for weight loss, comorbidities, quality of life, and complications. Excessive body mass index loss was similar between LSG and LRYGB at each time point (1 year: 72.3 ± 21.9% vs. 76.6 ± 20.9%, P = 0.139; 2 years: 74.7 ± 29.8% vs. 77.7 ± 30%, P = 0.513; 3 years: 70.9 ± 23.8% vs. 73.8 ± 23.3%, P = 0.316). At this interim 3-year time point, comorbidities were significantly reduced and comparable after both procedures except for gastro-esophageal reflux disease and dyslipidemia, which were more successfully treated by LRYGB. Quality of life increased significantly in both groups after 1, 2, and 3 years postsurgery. There was no statistically significant difference in number of complications treated by reoperation (LSG, n = 9; LRYGB, n = 16, P = 0.15) or number of complications treated conservatively. In this trial, LSG and LRYGB are equally efficient regarding weight loss, quality of life, and complications up to 3 years postsurgery. Improvement of comorbidities is similar except for gastro-esophageal reflux disease and dyslipidemia that appear to be more successfully treated by LRYGB.

With the increasing prevalence of obesity and a possible association with increasing sucrose consumption, nonnutritive sweeteners are gaining popularity. Given that some studies indicate that artificial sweeteners might have adverse effects, alternative solutions are sought. Xylitol and erythritol have been known for a long time and their beneficial effects on caries prevention and potential health benefits in diabetic patients have been demonstrated in several studies. Glucagon-like peptide-1 (GLP-1) and cholecystokinin (CCK) are released from the gut in response to food intake, promote satiation, reduce gastric emptying (GE), and modulate glucose homeostasis. Although glucose ingestion stimulates sweet taste receptors in the gut and leads to incretin and gastrointestinal hormone release, the effects of xylitol and erythritol have not been well studied. Ten lean and 10 obese volunteers were given 75 g of glucose, 50 g of xylitol, or 75 g of erythritol in 300 ml of water or placebo (water) by a nasogastric tube. We examined plasma glucose, insulin, active GLP-1, CCK, and GE with a [¹³C]sodium acetate breath test and assessed subjective feelings of satiation. Xylitol and erythritol led to a marked increase in CCK and GLP-1, whereas insulin and plasma glucose were not (erythritol) or only slightly (xylitol) affected. Both xylitol and erythritol induced a significant retardation in GE. Subjective feelings of appetite were not significantly different after carbohydrate intake compared with placebo. In conclusion, acute ingestion of erythritol and xylitol stimulates gut hormone release and slows down gastric emptying, whereas there is no or only little effect on insulin release.

Xylitol and erythritol are widely used in a variety of food and oral care products as sugar substitutes. Although a number of studies have been conducted on the health benefits of xylitol since the 1960s, erythritol only attracted the attention of researchers during the early 1990s. Historically, researchers mainly focused on the effects of xylitol and other sugar alcohols on oral and dental healthcare while the anti-diabetic or antihyperglycemic effects have only been revealed recently. Though a few reviews have been published on the health benefits of sugar alcohols in the last few decades, none of them closely evaluated the antihyperglycemic potential and underlying mechanisms, particularly with a focus on xylitol and erythritol. The current review thoroughly analyzes the anti-diabetic and antihyperglycemic effects as well as other metabolic effects of xylitol and erythritol using articles published in PubMed since the 1960s, containing research done on experimental animals and humans. This review will help researchers ascertain the controversies surrounding sugar alcohols, investigate further beneficial effects of them as well as aid food industries in exploring the possibilities of using sugar alcohols as anti-diabetic supplements in diabetic foods and food products.