The insulin tolerance test in morbidly obese patients undergoing bariatric surgery

Effects of bariatric surgery on glucose homeostasis and type 2 diabetes

Obesity is an important risk factor for type 2 diabetes mellitus (T2DM). Weight loss improves the major factors involved in the pathogenesis of T2DM, namely insulin action and beta cell function, and is considered a primary therapy for obese patients who have T2DM. Unfortunately, most patients with T2DM fail to achieve successful weight loss and adequate glycemic control from medical therapy. In contrast, bariatric surgery causes marked weight loss and complete remission of T2DM in most patients. Moreover, bariatric surgical procedures that divert nutrients away from the upper gastrointestinal tract are more successful in producing weight loss and remission of T2DM than those that simply restrict stomach capacity. Although upper gastrointestinal tract bypass procedures alter the metabolic response to meal ingestion, by increasing early postprandial plasma concentrations of glucagon-like peptide 1 and insulin, it is not clear whether these effects make an important contribution to long-term control of glycemia and T2DM once substantial surgery-induced weight loss has occurred. Nonetheless, the effects of surgery on body weight and metabolic function indicate that bariatric surgery should be part of the standard therapy for T2DM. More research is needed to advance our understanding of the physiological effects of different bariatric surgical procedures and possible weight loss-independent factors that improve metabolic function and contribute to the resolution of T2DM.

Nutritional status, genetic susceptibility, and insulin resistance--important precedents to atherosclerosis

Atherosclerosis is a progressive disease that starts early in life and is manifested clinically as coronary artery disease (CAD), cerebrovascular disease, or peripheral artery disease. CAD remains the leading cause of morbidity and mortality in Western society despite the great advances made in understanding its underlying pathophysiology. The key risk factors associated with CAD include hypercholesterolemia, hypertension, poor diet, obesity, age, male gender, smoking, and physical inactivity. Genetics also play an important role that may interact with environmental factors, including diet, nutritional status, and physiological parameters. Furthermore, certain chronic inflammatory conditions also predispose to the development of CAD. The spiraling increase in obesity rates worldwide has made it more pertinent than ever before to understand the metabolic perturbations that link over nutrition to enhanced cardiovascular risk. Great breakthroughs have been made at the pharmacological level to manage CAD; statins and aspirin have revolutionized treatment of CAD and prolonged lifespan. Nonetheless, lifestyle intervention prior to clinical presentation of CAD symptoms would negate/delay the need for chronic pharmacotherapy in at-risk individuals which in turn would relieve healthcare systems of a costly burden. Throughout this review, we debate the relative impact of nutrition versus genetics in driving CAD. We will investigate how overnutrition affects adipose tissue biology and drives IR and will discuss the subsequent implications for the cardiovascular system. Furthermore, we will discuss how lifestyle interventions including diet modification and weight loss can improve both IR and metabolic dyslipidemia that is associated with obesity. We will conclude by delving into the concept that nutritional status interacts with genetic susceptibility, such that perhaps a more personalized nutrition approach may be more effective in determining diet-related risk as well as response to nutritional interventions.

Mechanisms of improved glycaemic control after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) greatly improves glycaemic control in morbidly obese patients with type 2 diabetes, in many even before significant weight loss. Understanding the responsible mechanisms may contribute to our knowledge of the pathophysiology of type 2 diabetes and help identify new drug targets or improve surgical techniques. This review summarises the present knowledge based on pathophysiological studies published during the last decade. Taken together, two main mechanisms seem to be responsible for the early improvement in glycaemic control after RYGB: (1) an increase in hepatic insulin sensitivity induced, at least in part, by energy restriction and (2) improved beta cell function associated with an exaggerated postprandial glucagon-like peptide 1 secretion owing to the altered transit of nutrients. Later a weight loss induced improvement in peripheral insulin sensitivity follows.

Advances in the etiology and management of hyperinsulinemic hypoglycemia after Roux-en-Y gastric bypass

INTRODUCTION

Hyperinsulinemic hypoglycemia with severe neuroglycopenia has been identified as a late complication of Roux-en-Y gastric bypass (RYGB) in a small number of patients.

DISCUSSION

The rapid resolution of type 2 diabetes mellitus after RYGB is probably related to increased secretion of the incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), and patients with post-RYGB hypoglycemia demonstrate prolonged elevations of GIP and GLP-1 compared to non-hypoglycemic post-RYGB patients. Nesidioblastosis has been identified in some patients with post-RYGB hypoglycemia and is likely due to the trophic effects of GIP and GLP-1 on pancreatic islets.

CONCLUSIONS

Treatment of hypoglycemia after RYGB should begin with strict dietary (low carbohydrate) alteration and may require a trial of diazoxide, octreotide, or calcium-channel antagonists, among other drugs. Surgical therapy should include consideration of a restrictive form of bariatric procedure, with or without reconstitution of gastrointestinal continuity. Partial or total pancreatic resection should be avoided.

The effects of an amino acid supplement on glucose homeostasis, inflammatory markers, and incretins after laparoscopic gastric bypass

BACKGROUND

Protein supplements are routinely used after a laparoscopic gastric bypass (LGB). The aim of this study was to evaluate the impact of an amino acid supplement on glucose homeostasis and hormonal and inflammatory markers after LGB.

STUDY DESIGN

Thirty patients undergoing LGB were randomized to receive or not 24 g of an oral supplement containing a leucine metabolite, glutamine, and arginine twice daily. Changes in weight, glucose, insulin, C-peptide, insulin sensitivity, interleukin (IL) 6, C-reactive protein (CRP), leptin, insulin-like growth factor (IGF) 1, ghrelin, and incretins were assessed preoperatively and 2 weeks and 8 weeks postoperatively.

RESULTS

Thirty patients (96.7% female, age 46.9 ± 8.4 years, body mass index 43.3 ± 4.1 kg/m(2)) were randomized. The experimental (n = 14) and control (n = 16) groups were not significantly different at baseline. Weight loss was similar for the 2 groups. Fasting glucose decreased significantly at 2 and 8 weeks compared with base line (p < 0.0001) with no difference between the experimental and control groups (p = 0.8), but insulin and calculated insulin sensitivity, which were similar at baseline, became significantly worse in the experimental group 8 weeks after surgery (p = 0.02 for insulin; p = 0.04 for the homeostasis model assessment of insulin resistance). CRP and IL-6, which were similar at baseline, were found to be significantly higher at 8 weeks in the experimental group (p = 0.018 and p = 0.05, respectively). Leptin and IGF-1 levels decreased significantly from baseline at 2 and 8 weeks (p < 0.0001), but there was no difference between the 2 groups. No significant changes in GLP-1, ghrelin, or gastric inhibitory polypeptide were noticed after 8 weeks.

CONCLUSIONS

An amino acid supplement had no effect on the early postoperative incretins after LGB. It may have a negative influence on glucose kinetics and degree of inflammation. Future studies are needed to clarify these effects.

Nutritional assessment of bariatric surgery patients presenting for plastic surgery: a prospective analysis

BACKGROUND

Assessment of nutritional status in the growing postbariatric patient population remains controversial. Previous literature suggests that these patients have poor nutrition that may have adverse effects on surgical outcomes. The authors sought to determine the optimal method of nutritional assessment in postbariatric patients.

METHODS

One hundred patients presenting for body contouring after bariatric surgery were consecutively enrolled in an institutional review board-approved prospective study. A trained nutritionist assessed protein and calorie intake. All patients underwent baseline laboratory assessment.

RESULTS

Eighteen percent of subjects had less than the recommended daily protein intake. Hypoalbuminemia was observed in 13.8 percent of subjects, with hypoprealbuminemia in 6.5 percent. Nearly forty percent of all patients had evidence of iron deficiency, with vitamin B12 deficiency present in 14.5 percent. Ten percent of subjects (all women) were confirmed to have iron deficiency anemia. Impaired fasting glucose was seen in 6.2 percent of subjects, whereas 3.6 percent had hemoglobin A1c levels greater than 6.5. Increasing age (odds ratio, 1.07) and greater change in body mass index (odds ratio, 1.11) were predictors of low protein intake. Dumping syndrome led to 13.3 times increased odds of low albumin levels.

CONCLUSIONS

The results suggest that inadequate nutrition is common among postbariatric patients presenting for body contouring. The lack of correlation between methods of nutritional assessment supports the combination of multiple methods in determining overall nutritional status. The presence of dumping syndrome, a large change in body mass index, and advanced age may help to identify patients with an increased risk of nutritional deficiency.

Overcoming metabolic syndrome in severe obesity: adiponectin as a marker of insulin sensitivity and HDL-cholesterol improvements after gastric bypass

OBJECTIVE

To assess the relationship between adiponectin and metabolic parameters in severely obese women during surgical-induced weight loss.

METHODS

Nineteen lean (CT - BMI:21.2 +/- 0.3 kg.m(2)), 14 overweight/class II obese (OB/OW - BMI: 29.7 +/- 0.7 kg/m(2)) and 8 morbidly obese (OBIII - BMI: 56.4 +/- 3.6 kg/m(2)) were evaluated by hyperinsulinemic-euglycemic clamp, adiponectin, and lipids. OBIII were evaluated at 5th and 16th month post-operatively.

RESULTS

Compared to lean, obese groups had lower adiponectin (OB/OW: 9.4 +/- 0.9, OBIII: 7.1 +/- 1.3 versus 12.2 +/- 0.9 ng/dL; p < 0.01), lower HDL-cholesterol (OB/OW:1.05 +/- 0.05, OBIII: 0.88 +/- 0.04 versus 1.22 +/- 0.07 mmol/L; p < 0.01) and insulin resistance-IR (glucose uptake, M-value - OB/OW: 43.6 +/- 2.7, OBIII: 32.4 +/- 3.2 versus 20.0 +/- 1.8 umol/kgFFM.min; p < 0.001). Considering all subjects, adiponectin levels were inversely correlated to BMI and waist circumference, and directly to M-value and HDL-cholesterol (p < 0.01). During weight loss, improvements in IR (Study III: 36.1 +/- 3.9 umol/kg/FFM.min, p < 0.0001), adiponectin (11.8 +/- 1.4 ng/dL, p = 0.006) and HDL-cholesterol were observed (1.10 +/- 0.04 mmol/L, p = 0.007). Moreover, HDL-cholesterol improvement was significantly and independently related to variations of adiponectin and BMI (r(2) = 0.86; p < 0.0002).

CONCLUSIONS

The improvements of IR and adiponectin were related to surgical-induced weight loss, suggesting an important role of adiponectin in HDL-cholesterol regulation.

Surgery for nonobese type 2 diabetic patients: an interventional study with duodenal-jejunal exclusion

BACKGROUND

A 24-week interventional prospective trial was performed to compare the benefits of open duodenal-jejunal exclusion surgery (GJB) with a matched control group on standard medical care.

METHODS

One-hundred eighty patients were screened for the surgical approach. Twelve patients accepted to be operated and presented the full eligibility criteria for surgery that includes overweight BMI (25-29.9 kg/m2), T2DM diagnosis for less than 15 years, insulin-treated patients, no history of major complications, preserved beta-cell function, and absence of autoimmunity. A matched control group (CG) of patients whom refused surgical treatment was placed to receive standard care. Patients had age of 50 (5) years, time of diagnosis 9 years (range, 3 to 15 years), time of insulin usage 6 months (range, 3 to 48 months), fasting glucose (FG), 9.8 (2.5) mg/dL, and glycated hemoglobin (A1C) 8.90 (2.12)%.

RESULTS

At 24 weeks after surgery, patients experienced greater reductions on FG (14% vs. 7% on CG), A1C (from 8.78 to 7.84 in GJB-p<0.01 and 8.93 to 8.71 in CG; p<0.05 between groups) and reductions on average daily insulin requirement (93% vs. 29%, p<0.01). Ten patients stopped insulin usage in GJB but they remain taking oral medications. No differences were observed in both groups regarding BMI, body distribution and composition, blood pressure, and lipids.

CONCLUSIONS

In conclusion, duodenal-jejunal exclusion was an effective treatment for nonobese T2DM subjects. GJB was superior to standard care in achieving better glycemic control along with reduction in insulin requirements.

Do Incretins play a role in the remission of type 2 diabetes after gastric bypass surgery: What are the evidence?

Gastric bypass surgery (GBP), in addition to weight loss, results in dramatic remission of type 2 diabetes (T2DM). The mechanisms by which this remission occurs are unclear. Besides weight loss and caloric restriction, the changes in gut hormones that occur after GBP are increasingly gaining recognition as key players in glucose control. Incretins are gut peptides that stimulate insulin secretion postprandially; the levels of these hormones, particularly glucagon-like peptide-1, increase after GBP in response to nutrient stimulation. Whether these changes are causal to changes in glucose homeostasis remain to be determined. The purpose of this review is to assess the evidence on incretin changes and T2DM remission after GBP, and the possible mechanisms by which these changes occur. Our goals are to provide a thorough update on this field of research so that recommendations for future research and criteria for bariatric surgery can be evaluated.

Bariatric surgery does not cure all type 2 diabetes

Bariatric surgery is a treatment increasingly used for morbid obesity and a significant number of patients undergoing this procedure will have diabetes. While bariatric surgery has been shown to be one of the most effective treatments for long term weight control, it has also been shown that it leads to improvements in comorbidities associated with obesity including type 2 diabetes. In fact one large series showed that over 80% of patients treated with gastric bypass procedures no longer required treatment for their diabetes. We report the case of a patient with insulin-treated type 2 diabetes who underwent gastric banding and 2 days post-operatively presented with severe diabetic ketoacidosis.

Análise da função respiratória em pacientes obesos submetidos à operação Fobi-Capella

INTRODUÇÃO: O objetivo deste trabalho foi mensurar quantitativamente essas alterações respiratórias desses pacientes comparando-os até 30 dias de pós-operatório. MÉTODO: Foram realizadas avaliações respiratórias nos períodos pré e pós-operatório de cirurgia bariátrica em obesos mórbidos com IMC superior a 39kg/m², através de gasometria arterial, prova de função respiratória, manovacuômetria, incentivador da respiração e cirtometrias. Foram realizadas também orientações fisioterápicas respiratórias e tratamento no pós-operatório, com dados comparativos entre as avaliações feitas no préoperatório, no 1º, 14º·e 30º dia pós-operatórios. RESULTADOS: Até o 30º dia de pós-operatório, esses indivíduos não obtiveram diferença significativa nos parâmetros estudados, não havendo, em decorrência do tratamento fisioterápico, complicações respiratórias. CONCLUSÃO: Não houve alterações dos parâmetros analisados, nem complicações respiratórias neste estudo com intervenção fisioterápica pré e pós-operatório de cirurgia bariátrica. Estudos devem ser realizados, para mensuração de um tempo maior de pós-operatório e de exercícios específicos, podendo, assim apresentar resultados diferentes.

Insulin resistance and body composition in Turner syndrome: Effect of sequential change in the route of estrogen administration

The aim of the present study was to examine the impact of sequential change in the route of estrogen administration on body composition and insulin resistance in patients with Turner syndrome (TS) using cyclical hormone replacement therapy (HRT) with conjugated equine estrogens (CEE) plus medroxyprogesterone acetate (MPA). We carried out a self-controlled study of nine non-obese patients with TS, with an average age of 23 +/- 4.9 years. Body mass index (BMI), waist-to-hip ratio (WHR), fasting glycemia, insulin tolerance (glucose disappearance constant during an insulin tolerance test, kITT) and body composition (dual-energy X-ray absorptiometry) were studied after 1 year's use of CEE plus MPA and repeated after 1 year's use of 17beta-estradiol gel with the same schedule of MPA administration. We did not observe any difference between the oral and percutaneous HRT with regard to BMI, WHR and insulin tolerance (kITT: 4.9 +/- 1.5 vs. 5.3 +/- 1.5%/min, p = 0.8). During administration of the 17beta-estradiol gel a tendency to increased total lean mass (p = 0.054) was observed. We conclude that sequential change in the route of estrogen administration in TS patients using cyclical HRT with CEE and MPA does not affect insulin resistance, although use of percutaneous 17beta-estradiol gel seems to exert favorable changes in body composition.

[Does bariatric surgery cure the metabolic syndrome?]

Metabolic syndrome (MS) is a risk condition for the development of systemic atherosclerotic disease. Morbid obesity is a state of insulin resistance (IR) associated with visceral fat accumulation, which is involved in the development of MS. In severe obesity, conservative therapies promote an improvement of MS, but weight regain is frequent, whereas bariatric surgery promotes a more significant and sustained weight loss. Bariatric surgery is recommended for patients with unsatisfactory response to clinical treatment and with IMC > 40 kg/m(2) or > 35 in case of co-morbidities. In those cases, surgical risk must be acceptable and patients submitted to surgery must be informed about complications and postoperative care. Prevention, improvement and reversion of diabetes (DM2) (70 to 90% of cases) are seen in several bariatric surgery modalities. Disabsorptive are more efficient than restrictive procedures in terms of weight reduction and insulin sensitivity improvement, but chronic complications, such as malnutrition, are also more frequent. Vertical gastroplasty with jejunoileal derivation is a mixed surgery in which the restrictive component predominates. In this modality, reversion of DM2 is due to an increase in insulin sensitivity associated with improved beta cell function. Reversion of MS and its manifestations after bariatric surgery are associated with reduction of cardiovascular mortality and, thus, in severe obesity cases, MS can be considered a surgical condition.

Avaliação laboratorial e diagnóstico da resistência insulínica

Em virtude da associação entre resistência à insulina (RI) e aterosclerose, existe interesse no desenvolvimento de técnicas para se avaliar a sensibilidade à insulina (SI) in vivo. Por ser uma medida de fácil utilização em grandes populações, a insulinemia de jejum tem sido usada para avaliar a SI e fornece uma boa avaliação da sensibilidade hepática, embora não da muscular. O HOMA é um modelo matemático que prediz a SI pelas simples medidas da glicemia e da insulina no jejum e tem boa correlação com o método do clamp euglicêmico hiperinsulinêmico, considerado padrão-ouro na medida da SI. Assim, mostra-se como valiosa alternativa às técnicas mais sofisticadas e trabalhosas na avaliação da RI em humanos, como o método descrito por Bergman. Em nosso meio, encontramos o valor de corte para o diagnóstico da RI quando o Homa-IR for maior que 2,71. O QUICKI é outro método simples, baseado também nas medidas da glicemia e da insulina no jejum, que apresenta boas correlações com marcadores da síndrome metabólica, conseguindo discriminar satisfatoriamente diferentes estados de RI, como graus de obesidade e tolerância à glicose. Métodos diretos de avaliação da SI incluem o teste de tolerância à insulina (K ITT), o teste de supressão de insulina e as técnicas de clamp hiperglicêmico e euglicêmico que são descritas neste artigo. A técnica do clamp euglicêmico e hiperinsulinêmico fornece a mais pura e reprodutível informação sobre a ação da insulina. Os custos envolvidos na sua realização, entretanto, limitam o seu uso.

BMI is the main determinant of the circulating leptin in women after vertical banded gastroplasty

OBJECTIVE

To assess the main determinant of serum leptin concentration changes in morbidly obese patients treated by banded vertical gastroplasty.

RESEARCH METHODS AND PROCEDURES

Serum leptin and insulin concentrations, insulin resistance, BMI, body weight, and body fat mass in 18 obese women and 8 obese men treated by vertical banded gastroplasty were studied. Lean women and men subjects were used as controls.

RESULTS

Before surgery, serum leptin and insulin concentrations and insulin resistance index were significantly higher in morbidly obese patients than in control subjects. BMI, body fat mass, and serum triacylglycerol concentrations were also significantly higher in obese than in lean subjects. All of these parameters gradually decreased during 50 weeks after surgery. Univariate regression analysis displayed significant correlations between the following: serum leptin concentration and BMI (and body fat mass), serum leptin concentration and serum insulin concentration, and serum leptin concentration and insulin resistance index. Multivariate regression analysis indicated that only BMI was independently correlated with the decrease in serum leptin concentration.

DISCUSSION

Obtained data suggest the following: 1) vertical banded gastroplasty causes reduction of body weight, serum leptin and insulin concentration, insulin resistance, and serum triacylglycerol concentration; and 2) BMI is the main determinant of the circulating leptin concentration in morbidly obese women after anti-obesity surgery.

Sibutramine enhances insulin sensitivity ameliorating metabolic parameters in a double-blind, randomized, placebo-controlled trial

AIM

To assess the effect of sibutramine-assisted weight reduction program on insulin sensitivity and metabolic parameters in obese normal glucose tolerant individuals over a period of 24 weeks.

RESEARCH DESIGN AND METHODS

A double-blind, placebo-controlled, parallel, prospective clinical trial was carried out at our medical centre. Forty female normal glucose tolerant patients, body mass index: 34.3 +/- 2.9 kg/m2 and age: 41.1 +/- 9.9 (range: 19-58 years), were randomized to placebo or sibutramine, 10 mg once daily.

RESULTS

Seventeen patients from sibutramine group and 14 placebo had completed the study protocol. Significant weight change was seen in sibutramine (p < 0.01) (-5.6 kg or -6.1% vs. +0.9 kg or +1.1% in placebo). Insulin sensitivity enhanced in sibutramine group (Kitt: from 4.03 +/- 1.97 to 5.09 +/- 2.48%/min; p < 0.05). Homeostasis model assessment-IR (HOMA-IR) decreased from 7.8 +/- 6.9 to 5.6 +/- 4.5 (p < 0.05). HOMA-beta also decreased from 508 +/- 381 to 374 +/- 256 (p < 0.05). No changes were observed in the placebo control group regarding insulin sensitivity or secretion. Concomitant reductions were observed in the sibutramine group in lipid parameters (triglycerides and high-density lipoprotein-cholesterol), uric acid and gamma-glutamyl transferase (p < 0.05).

CONCLUSIONS

Sibutramine has demonstrated efficacy in reducing weight in non-diabetic women along with amelioration in insulin sensitivity and additional improvement in metabolic parameters.