***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Marked improvement in glycemic control occurs in patients with type 2 diabetes mellitus shortly after Roux-en-Y gastric bypass surgery ( RYGB )  and before there is major weight loss . The objective of this study was to determine whether the magnitude of this change is primarily due to caloric restriction or is unique to the surgical procedure . We studied eleven subjects who underwent RYGB and fourteen subjects mean-matched for BMI , HbA1c , and diabetes duration who were admitted to our inpatient research unit and given a very low – calorie diet ( VLCD ) of 500 kcal/day with a macronutrient content similar to that consumed by patients after RYGB . Frequently sample d intravenous glucose tolerance tests were performed before and after interventions . Both groups lost an equivalent amount of weight over a mean study period of 21 days . Insulin sensitivity , acute insulin secretion after intravenous glucose administration , and β-cell function as determined by disposition index improved to a similar extent in both groups . Likewise , changes in fasting glucose and fructosamine levels were similar . Based on these data , VLCD improves insulin sensitivity and β-cell function just as well as RYGB in the short term Although moderate weight loss improves glycemic control in obese NIDDM patients , quite often it is not normalized . To determine whether the response to weight loss can be improved by altering the macronutrient composition of hypocaloric diets , 17 obese NIDDM patients were studied at 1 ) baseline , 2 ) after dieting for 6 weeks on a formula diet enriched in either monounsaturated fatty acids ( MUFAs , n = 9 ) or carbohydrates ( CHOs , n = 8) at a 50 % caloric deficit , and 3 ) after 4 weeks of postdiet refeeding on the respective formulas with caloric intake titrated to achieve weight maintenance . Fasting , 24-h , and oral glucose tolerance test ( OGTT ) blood glucose , plasma insulin , and C-peptide levels were measured . All prediet parameters were similar between groups . After dieting , although weight loss was similar between groups , the fasting glucose level decreased significantly more in the MUFA group ( −4.6 ± 0.7 mmol/l ) than in the CHO group ( −2.4 ± 1.0 mmol/l ; P < 0.05 ) . Twenty-four – hour glycemia decreased in both groups after dieting , but the MUFA group had a greater decrease than the CHO group ( P < 0.05 , analysis of variance [ ANOVA ] ) . Although decreases in fasting glycemia were maintained in both groups after refeeding , postpr and ial glycemia deteriorated after refeeding with the CHO- but not the MUFA-enriched formula ( P < 0.05 ) . After dieting and refeeding , fasting C-peptide increased 204 ± 47 pmol/l in the MUFA group , but the CHO group remained at prediet levels ( P < 0.05 ) . Twenty-four-hour C-peptide levels were similar between groups after dieting and refeeding , despite the lower glycemia and CHO content of the MUFA formula . However , when equal amounts of CHO were consumed during the OGTT , the MUFA group had significantly higher C-peptide levels after both dieting and refeeding ( P < 0.05 ) . Fasting , 24-h , and OGTT insulin levels were similar between groups throughout the study . These results indicate that macronutrient composition is an important determinant of the glycemic response to weight-loss therapy in obese NIDDM patients . Based on the C-peptide response during the OGTT , increased CHO-induced insulin secretion is one possible mechanism by which this occurs There has been interest in the effect of various types and amounts of dietary carbohydrates and proteins on blood glucose . On the basis of our previous data , we design ed a high-protein/low-carbohydrate , weight-maintaining , nonketogenic diet . Its effect on glucose control in people with untreated type 2 diabetes was determined . We refer to this as a low-biologically-available-glucose ( LoBAG ) diet .  Eight men were studied using a r and omized 5-week crossover design with a 5-week washout period . The carbohydrate : protein : fat ratio of the control diet was 55:15:30 . The test diet ratio was 20:30:50 . Plasma and urinary beta-hydroxybutyrate were similar on both diets . The mean 24-h integrated serum glucose at the end of the control and LoBAG diets was 198 and 126 mg/dl , respectively . The percentage of glycohemoglobin was 9.8 + /- 0.5 and 7.6 + /- 0.3 , respectively . It was still decreasing at the end of the LoBAG diet . Thus , the final calculated glycohemoglobin was estimated to be approximately 6.3 - 5.4 % . Serum insulin was decreased , and plasma glucagon was increased . Serum cholesterol was unchanged . Thus , a LoBAG diet ingested for 5 weeks dramatically reduced the circulating glucose concentration in people with untreated type 2 diabetes . Potentially , this could be a patient-empowering way to ameliorate hyperglycemia without pharmacological intervention . The long-term effects of such a diet remain to be determined Rapid glycemic improvements following Roux-en-Y gastric bypass ( RYGB ) are frequently attributed to the enhanced GLP-1 response , but causality remains unclear . To determine the role of GLP-1 in improved glucose tolerance after surgery , we compared glucose and hormonal responses to a liquid meal test in 20 obese participants with type 2 diabetes mellitus who underwent RYGB or nonsurgical intensive lifestyle modification ( ILM ) ( n = 10 per group ) before and after equivalent short-term weight reduction . The GLP-1 receptor antagonist exendin(9–39)-amide ( Ex-9 ) was administered , in r and om order and in double-blinded fashion , with saline during two separate visits after equivalent weight loss . Despite the markedly exaggerated GLP-1 response after RYGB , changes in postpr and ial glucose and insulin responses did not significantly differ between groups , and glucagon secretion was paradoxically augmented after RYGB . Hepatic insulin sensitivity also increased significantly after RYGB . With Ex-9 , glucose tolerance deteriorated similarly from the saline condition in both groups , but postpr and ial insulin release was markedly attenuated after RYGB compared with ILM . GLP-1 exerts important insulinotropic effects after RYGB and ILM , but the enhanced incretin response plays a limited role in improved glycemia shortly after surgery . Instead , enhanced hepatic metabolism , independent of GLP-1 receptor activation , may be more important for early postsurgical glycemic improvements BACKGROUND Biliopancreatic diversion ( BPD ) is the most effective bariatric procedure in terms of weight loss and remission of diabetes type 2 ( T2DM ) , but it is accompanied by nutrient deficiencies . Sleeve gastrectomy ( SG ) is a relatively new operation that has shown promising results concerning T2DM resolution and weight loss . The objective of this study was to evaluate and compare prospect ively the effects of BPD long limb ( BPD ) and laparoscopic SG on fasting , and glucose-stimulated insulin , glucagon , ghrelin , peptide YY ( PYY ) , and glucagon-like peptide-1 ( GLP-1 ) secretion and also on remission of T2DM , hypertension , and dyslipidemia in morbidly obese patients with T2DM . METHODS Twelve patients ( body mass index [ BMI ] 57.6 ± 9.9 kg/m(2 ) ) underwent BPD and 12 ( BMI 43.7 ± 2.1 kg/m(2 ) ) underwent SG . All patients had T2DM and underwent an oral glucose tolerance test ( OGTT ) before and 1 , 3 , and 12 months after surgery . RESULTS BMI decreased more after BPD , but percent excess weight loss ( % EWL ) was similar in both groups ( P = .8 ) and T2DM resolved in all patients at 12 months . Insulin sensitivity improved more after BPD than after SG ( P = .003 ) . Blood pressure , total and LDL cholesterol decreased only after BPD ( P<.001 ) . Triglycerides decreased after either operation , but HDL increased only after SG ( P<.001 ) . Fasting ghrelin did not change after BPD ( P = .2 ) , but decreased markedly after SG ( P<.001 ) . GLP-1 and PYY responses during OGTT were dramatically enhanced after either procedure ( P = .001 ) . CONCLUSIONS SG was comparable to BPD in T2DM resolution but inferior in improving dyslipidemia and blood pressure . SG and BPD enhanced markedly PYY and GLP-1 responses but only SG suppressed ghrelin levels BACKGROUND Type 2 diabetes mellitus is increasingly common , primarily because of increases in the prevalence of a sedentary lifestyle and obesity . Whether type 2 diabetes can be prevented by interventions that affect the lifestyles of subjects at high risk for the disease is not known . METHODS We r and omly assigned 522 middle-aged , overweight subjects ( 172 men and 350 women ; mean age , 55 years ; mean body-mass index [ weight in kilograms divided by the square of the height in meters ] , 31 ) with impaired glucose tolerance to either the intervention group or the control group . Each subject in the intervention group received individualized counseling aim ed at reducing weight , total intake of fat , and intake of saturated fat and increasing intake of fiber and physical activity . An oral glucose-tolerance test was performed annually ; the diagnosis of diabetes was confirmed by a second test . The mean duration of follow-up was 3.2 years . RESULTS The mean ( + /-SD ) amount of weight lost between base line and the end of year 1 was 4.2+/-5.1 kg in the intervention group and 0.8+/-3.7 kg in the control group ; the net loss by the end of year 2 was 3.5+/-5.5 kg in the intervention group and 0.8+/-4.4 kg in the control group ( P<0.001 for both comparisons between the groups ) . The cumulative incidence of diabetes after four years was 11 percent ( 95 percent confidence interval , 6 to 15 percent ) in the intervention group and 23 percent ( 95 percent confidence interval , 17 to 29 percent ) in the control group . During the trial , the risk of diabetes was reduced by 58 percent ( P<0.001 ) in the intervention group . The reduction in the incidence of diabetes was directly associated with changes in lifestyle . CONCLUSIONS Type 2 diabetes can be prevented by changes in the lifestyles of high-risk subjects OBJECTIVE Hyperglycemia improves when patients with type 2 diabetes are placed on a weight-loss diet . Improvement typically occurs soon after diet implementation . This rapid response could result from low fuel supply ( calories ) , lower carbohydrate content of the weight-loss diet , and /or weight loss per se . To differentiate these effects , glucose , insulin , C-peptide and glucagon were determined during the last 24 h of a 3-day period without food ( severe calorie restriction ) and a calorie-sufficient , carbohydrate-free diet . RESEARCH DESIGN Seven subjects with untreated type 2 diabetes were studied . A r and omized-crossover design with a 4-week washout period between arms was used . METHODS Results from both the calorie-sufficient , carbohydrate-free diet and the 3-day fast were compared with the initial st and ard diet consisting of 55 % carbohydrate , 15 % protein and 30 % fat . RESULTS The overnight fasting glucose concentration decreased from 196 ( st and ard diet ) to 160 ( carbohydrate-free diet ) to 127 mg/dl ( fasting ) . The 24 h glucose and insulin area responses decreased by 35 % and 48 % on day 3 of the carbohydrate-free diet , and by 49 % and 69 % after fasting . Overnight basal insulin and glucagon remained unchanged . CONCLUSIONS Short-term fasting dramatically lowered overnight fasting and 24 h integrated glucose concentrations . Carbohydrate restriction per se could account for 71 % of the reduction . Insulin could not entirely explain the glucose responses . In the absence of carbohydrate , the net insulin response was 28 % of the st and ard diet . Glucagon did not contribute to the metabolic adaptations observed Objective : To evaluate the physiologic importance of the satiety gut hormones . Background : Controversy surrounds the physiologic role of gut hormones in the control of appetite . Bariatric surgery remains the most effective treatment option for obesity , and gut hormones are implicated in the reduction of appetite and weight after Roux-en-Y gastric bypass . Methods : We correlated peptide YY ( PYY ) and glucagon-like pe 
    Output:
    
Conclusions Synergistic suppression of fasting glucagon and insulin resistance may act together to restore normoglycaemia following weight loss .
Whether suppression of plasma glucagon may contribute to increased hunger after weight loss and gradual weight regain is not yet known