Surgical treatment of type 2 diabetes in subjects with mild obesity: mechanisms underlying metabolic improvements.

BACKGROUND: This study aims to assess the clinical and physiological effects of Roux-en-Y gastric bypass (RYGBP) on type 2 diabetes associated with mild obesity (body mass index [BMI] 30-34.9 kg/m(2)) over 24 months postsurgery. METHODS: In this prospective trial, 36 mildly obese subjects (19 males) with type 2 diabetes using oral antidiabetic drugs with (n = 24) or without insulin (n = 12) underwent RYGBP. Follow-up was conducted at baseline and 3, 6, 12, and 24 months postsurgery. The following endpoints were considered: changes in HbA1c, fasting glucose and insulin, antidiabetic therapy, BMI, oral glucose insulin sensitivity [OGIS, from meal tolerance test (MTT)], beta-cell secretory function [ΔCP(0-30)/ΔGlu(0-30) (ΔC-peptide/Δglucose ratio, MTT 0-30 min), disposition index (DI = OGIS [Symbol: see text] ΔCP(0-30)/ΔGlu(0-30)], glucagon-like peptide (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) [incremental area under the curve (AUCi)], adiponectin, C-reactive protein, and lipids. RESULTS: All subjects achieved normal-to-overweight BMI after 3 months. Over 24 months, 31/36 (86 %) subjects presented HbA1c <7 % [complete and partial remission of diabetes in 9/36 (22 %) and 1/36 (3 %), respectively]. Since 3 months postsurgery, improvements were observed in OGIS [290 (174) to 373 (77) ml/min/m(2), P = 0.009], ΔCP(0-30)/ΔGlu(0-30) [0.24 (0.19) to 0.52 (0.34) ng/mg, P = 0.001], DI [7.16 (8.53) to 19.8 (15.4) (ng/mg) (ml/min/m(2)), P = 0.001], GLP-1 AUCi [0.56 (0.64) to 3.97 (3.86) ng/dl [Symbol: see text] 10 min [Symbol: see text] 103, P = 0.000], and GIP AUCi [30.2 (12.6) to 27.0 (20.2) ng/dl [Symbol: see text] 10 min [Symbol: see text] 103, P = 0.004]. At baseline and after 12 months, subjects with diabetes nonremission had longer diabetes duration, higher HbA1c, lower beta-cell secretory function, and higher first 30-min GIP AUCi, compared with those with remission. CONCLUSIONS: RYGBP improves the glucose metabolism in subjects with type 2 diabetes and mild obesity. This effect is associated with improvement of insulin sensitivity, beta-cell secretory function, and incretin secretion.

Defective regulation of adipose tissue autophagy in obesity.

OBJECTIVES: Autophagy is a highly regulated process that has an important role in the control of a wide range of cellular functions, such as organelle recycling, nutrient availability and tissue differentiation. A recent study has shown an increased autophagic activity in the adipose tissue of obese subjects, and a role for autophagy in obesity-associated insulin resistance was proposed. Body mass reduction is the most efficient approach to tackle insulin resistance in over-weight subjects; however, the impact of weight loss in adipose tissue autophagy is unknown. SUBJECTS: Adipose tissue autophagy was evaluated in mice and humans. RESULTS: First, a mouse model of diet-induced obesity and diabetes was maintained on a 15-day, 40% caloric restriction. At baseline, markers of autophagy were increased in obese mice as compared with lean controls. Upon caloric restriction, autophagy increased in the lean mice, whereas it decreased in the obese mice. The reintroduction of ad libitum feeding was sufficient to rapidly reduce autophagy in the lean mice and increase autophagy in the obese mice. In the second part of the study, autophagy was evaluated in the subcutaneous adipose tissue of nine obese-non-diabetic and six obese-diabetic subjects undergoing bariatric surgery for body mass reduction. Specimens were collected during the surgery and approximately 1 year later. Markers of systemic inflammation, such as tumor necrosis factor-1α, interleukin (IL)-6 and IL-1ß were evaluated. As in the mouse model, human obesity was associated with increased autophagy, and body mass reduction led to an attenuation of autophagy in the adipose tissue. CONCLUSION: Obesity and caloric overfeeding are associated with the defective regulation of autophagy in the adipose tissue. The studies in obese-diabetic subjects undergoing improved metabolic control following calorie restriction suggest that autophagy and inflammation are regulated independently.

Cerebrospinal fluid xenin levels during body mass reduction: no evidence for obesity-associated defective transport across the blood-brain barrier.

CONTEXT: Recent studies have shown that xenin can act in the hypothalamus, reducing food intake through a leptin- and melanocortin system-independent mechanism. OBJECTIVE: To evaluate the impact of body mass reduction on the blood and cerebrospinal fluid (CSF) levels of xenin. DESIGN AND SETTING: Thirteen obese patients (11 women) selected for roux-in-Y gastric bypass surgery were evaluated before and approximately 8 months after surgery. Xenin was determined in serum and CSF by radioimmunoassay. RESULTS: As compared with lean subjects, obese patients have increased blood levels of xenin, which reduce after surgery. There are significant correlations between blood xenin and blood leptin and insulin levels. CSF concentration of xenin is ∼10-fold lower than blood levels, and is significantly higher in obese subjects as compared with lean ones, returning to normal levels after body mass reduction. There is a significant linear correlation between CSF and blood levels of xenin. CONCLUSION: Xenin is present in the human CSF in a concentration ∼10-fold lower than the blood. Both blood and CSF xenin are correlated with blood levels of important markers of adiposity, leptin and insulin. The levels of CSF xenin are linearly correlated with blood xenin, independently of patient body mass, suggesting that either its transport across the blood-brain barrier is not saturated in the concentration range detected in this study or that there is a coordinated release of xenin from the periphery and the CNS.

PGC1α gene Gly482Ser polymorphism predicts improved metabolic, inflammatory and vascular outcomes following bariatric surgery.

AIMS/HYPOTHESIS: Bariatric surgery is currently employed as an effective approach to treat class III obesity and class II obesity with co-morbidities. Unfortunately, the general anthropometric and metabolic outcomes of the surgery are not homogeneous, and defining the eligibility criteria that allow for a more precise prediction of the outcomes of this invasive procedure will refine the selection of patients. Here we tested the hypothesis that the Gly482Ser polymorphism of the ppargc1a gene would predict different outcomes following bariatric surgery. METHODS: Fifty-five patients (26 Gly/Gly and 29 Gly/Ser+Ser/Ser) selected for the Roux-en-Y gastric bypass according to the National Institutes of Health Consensus Statement criteria were followed up for 1 year, monitoring their anthropometric, metabolic and inflammatory parameters. RESULTS: Patients with the Gly482Ser polymorphism had significantly improved reductions in the waist/hip ratio, fasting blood glucose, C-reactive protein, blood leukocyte count, serum interleukin-6 and intima-media thickness of the carotid artery, as compared with Gly/Gly patients. CONCLUSIONS/INTERPRETATION: Thus, the Gly482Ser polymorphism may predict a more favorable metabolic and inflammatory outcome for obese patients submitted to bariatric surgery, leading to a reduced atherosclerotic risk.

Erectile dysfunction and hormonal imbalance in morbidly obese male is reversed after gastric bypass surgery: a prospective randomized controlled trial.

The effects of weight loss on erectile function and hormones have not been well studied. The aim of this study was to measure the degree to which sexual function and in particular erectile function and hormonal environment change after substantial weight loss, surgically and non-surgically induced in the morbidly obese male in a prospective randomized long-term controlled trial. Furthermore, how surgery makes a difference when treating morbidly obese men was envisaged in this context. We prospectively studied 20 morbidly obese men for 24 months, divided into two groups: group A included 10 patients who underwent life style modifications (exercise and diet) for 4 months and subsequently gastric bypass, and another 10 patients in group B were kept on weekly follow-up. None of the men were taking phosphodiesterase type-5 inhibitors. All patients underwent International Index of Erectile Function (IIEF)-5 questionnaire, serum oestradiol, prolactin (PRL), luteinizing (LH) and follicle-stimulating (FSH) hormones, free and total testosterone (FT and TT) at baseline (time 0), surgery - 4 months latter baseline (time 1) and final evaluation - 24 months (time 2). From times 0 to 1, group A presented a mean body mass index (BMI) reduction of 12.6 (p < 0.0001), whereas group B, 2.1 (p > 0.05). The BMI reductions between times 0 and 2 were 24.7 (p < 0.0001) and 0.7 (p > 0.05) for groups A and B respectively. BMI average between the two groups was similar at time 0 (p = 0.2142), and different at times 1 (p = 0.0033) and 2 (p < 0.0006). Increase in IIEF-5 score (p = 0.0469), TT (p = 0.0349) and FSH levels (p = 0.0025), and reduction in PRL level (p < 0.0001) were observed in group A from times 0 to 2 and 1 to 2. There were no changes from times 0 to 1. Comparing groups A and B at time 2, IIEF-5, TT and FT increased significantly in group A (p = 0.0224, 0.0043 and 0.0149 respectively). Surgery-induced weight loss increased erectile function quality measured by IIEF-5 questionnaire, increased TT, FT and FSH and reduced PRL levels. The hormonal impact verified could justify the improvement in erectile function. Lifestyle modifications impacted BMI without hormonal or sexual impact in morbidly obese. New studies are warranted in the field to support our data.

Restored insulin inhibition on insulin secretion in nondiabetic severely obese patients after weight loss induced by bariatric surgery.

OBJECTIVE: To examine the impact of important weight loss on insulin inhibition of its own secretion during experimentally induced hyperinsulinemia under euglycemic conditions. DESIGN: Longitudinal, clinical intervention study--bariatric surgery (vertical banded gastroplasty--gastric bypass--Capella technique), re-evaluation after 4 and 14 months. SUBJECTS: Nine obese patients class III (BMI=54.6+/-2.6 kg/m2) and nine lean subjects (BMI=22.7+/-0.7 kg/m2). MEASUREMENTS: Euglycemic hyperinsulinemic clamp (insulin infusion: 40 mU/min m2), C-peptide plasma levels, electrical bioimpedance methodology, and oral glucose tolerance test (OGTT). RESULTS: BMI was reduced in the follow-up: 44.5+/-2.2 and 33.9+/-1.5 kg/m2 at 4 and 14 months. Insulin-induced glucose uptake was markedly reduced in obese patients (19.5+/-1.9 micromol/min kg FFM) and improved with weight loss, but in the third study, it was still lower than that observed in controls (35.9+/-4.0 vs 52.9+/-2.2 micromol/min kg FFM). Insulin-induced inhibition of its own secretion was blunted in obese patients (19.9+/-5.7%, relative to fasting values), and completely reversed to values similar to that of lean ones in the second and third studies (-60.8+/-4.2 and -54.0+/-6.1%, respectively). CONCLUSION: Weight loss in severe obesity improved insulin-induced glucose uptake, and completely normalized the insulin inhibition on its own secretion.