Very-low-calorie diet: a quick therapeutic tool to improve β cell function in morbidly obese patients with type 2 diabetes

Anti-incretin, Anti-proliferative Action of Dopamine on β-Cells

Human islet β-cells exploit an autocrine dopamine (DA)-mediated inhibitory circuit to regulate insulin secretion. β-Cells also express the DA active transporter and the large neutral amino acid transporter heterodimer enabling them to import circulating DA or its biosynthetic precursor, L-3,4-dihydroxyphenylalanine (L-DOPA). The capacity to import DA or L-DOPA from the extracellular space possibly indicates that DA may be an endocrine signal as well. In humans, a mixed meal stimulus is accompanied by contemporary serum excursions of incretins, DA and L-DOPA, suggesting that DA may act as an anti-incretin as postulated by the foregut hypothesis proposed to explain the early effects of bariatric surgery on type 2 diabetes. In this report, we take a translational step backwards and characterize the kinetics of plasma DA and incretin production after a mixed meal challenge in a rat model and study the integration of incretin and DA signaling at the biochemical level in a rodent β-cell line and islets. We found that there are similar excursions of incretins and DA in rats, as those reported in humans, after a mixed meal challenge and that DA counters incretin enhanced glucose-stimulated insulin secretion and intracellular signaling at multiple points from dampening calcium fluxes to inhibiting proliferation as well as apoptosis. Our data suggest that DA is an important regulator of insulin secretion and may represent 1 axis of a gut level circuit of glucose and β-cell mass homeostasis.

Early improvement of postprandial lipemia after bariatric surgery in obese type 2 diabetic patients

BACKGROUND

Bariatric surgery (BS) is able to positively influence fasting lipid profile in obese type 2 diabetic patients (T2DM), but no data is available on the impact of BS on postprandial lipid metabolism neither on its relation with incretin hormones. We evaluated the short-term (2 weeks) effects of BS on fasting and postprandial lipid metabolism in obese T2DM patients and the contribution of changes in active GLP-1.

METHODS

We studied 25 obese T2DM patients (age = 46 ± 8 years, BMI = 44 ± 7 kg/m2), of which 15 underwent sleeve gastrectomy and 10 underwent gastric bypass. Lipid and incretin hormone concentrations were evaluated for 3 h after ingestion of a liquid meal before and 2 weeks after BS.

RESULTS

After BS, there was a significant reduction in body weight (p < 0.001), fasting plasma glucose (p < 0.001), fasting plasma insulin (p < 0.05), HOMA-IR (p < 0.001), and fasting plasma lipids (p < 0.05). The meal response of plasma triglycerides, total cholesterol, and HDL cholesterol was significantly lower compared to pre-intervention (p < 0.05, p < 0.001). In particular, the incremental area under the curve (IAUC) of plasma triglycerides decreased by 60% (p < 0.005). The meal-stimulated response of active GLP-1 increased, reaching a statistical significance (p < 0.001).

CONCLUSIONS

BS leads to an early improvement of fasting and postprandial lipemia. The fall in fasting triglycerides is associated with an improvement of insulin resistance, while the reduction of postprandial lipemia is likely related to reduced intestinal lipid absorption consequent to bariatric surgery.

A 2-Week Course of Enteral Treatment with a Very Low-Calorie Protein-Based Formula for the Management of Severe Obesity

Background. Multiple weight loss failures among obese patients suggest the design of new therapeutic strategies. We investigated the role of 2-week course of enteral treatment with a very low-calorie protein-based formula in the management of severe obesity. Methods. We evaluated the feasibility, safety, and efficacy of 2-week continuous administration of a protein-based formula (1.2 g/kg of ideal body weight/day) by nasogastric tube in severely obese adults (body mass index (BMI) ≥ 40 kg/m(2)). Results. In total, 364 patients (59% women; BMI = 46.6 ± 7.2 kg/m(2)) were recruited. The intervention was discontinued within 48 hours in 26 patients, due to nasogastric tube intolerance. No serious adverse events occurred. During the first and the second week, 65% and 80% patients, respectively, reported no side effects. All biochemical safety parameters were affected by the intervention, particularly uric acid (+45%) and aminotransferases (+48%). In the other cases the change was negligible. We observed significant weight loss (5.7 ± 2.3%) and improvement in blood pressure and glucose and lipid metabolism parameters (P < 0.001). Conclusions. A 2-week course of enteral treatment with a very low-calorie protein-based formula appeared a feasible, likely safe, and efficacious therapeutic option to be considered for inclusion into a composite weight loss program for the management of severe obesity. This trial is registered with ClinicalTrials.gov Identifier: NCT01965990.

Acute hyperglycemia reduces cerebrovascular reactivity: the role of glycemic variability

CONTEXT

Cerebral vasomotor reactivity (CVR) is reduced in patients with diabetes mellitus (DM), and glucose variability (GV) might be responsible for cerebrovascular damage.

OBJECTIVE

Studying patients with insulin resistance without DM, we explored the role of GV in impairing CVR.

PATIENTS

We studied 18 metabolic syndrome (MS) patients without DM, 9 controls (C), and 26 patients with DM.

MAIN OUTCOME MEASURES

Groups were compared in terms of CVR, GV, and 24-hour blood pressure. To evaluate the impact of acute hyperglycemia on CVR, a hyperglycemic clamp was performed in MS patients and controls.

RESULTS

Baseline CVR was reduced in DM vs C and MS (C vs DM = 20.2, 95% CI = 3.5-36.9, P = .014; and MS vs DM = 22.2, 95% CI = 8.6-35.8, P = .001), but similar between MS and C (MS vs C = 2.0, 95% CI = -14.7 to 18.7, P = .643). During acute hyperglycemia, CVR fell in MS and C to values comparable to DM. GV progressively increased from C to MS to DM. In MS, CVR at 120 minutes and GV displayed a negative correlation (r = -0.48, P = .043), which did not change after controlling for mean 24-hour systolic and diastolic blood pressure. In MS, the CVR reduction was significantly correlated to GV (r = 0.55, P = .02).

CONCLUSIONS

GV is increased in patients with MS but without DM and is the major predictor of CVR reduction induced by acute hyperglycemia, possibly representing the earliest cause of cerebrovascular damage in DM.

Short-term calorie restriction improves glucose homeostasis in old rats: involvement of AMPK

The occurrence of metabolic disorders, such as diabetes, obesity, atherosclerosis, and hypertension, increases with age. Inappropriate food intake, when combined with genetic and hormonal factors, can trigger the occurrence of these diseases in aged organisms. This study investigated whether short-term calorie restriction (CR; 40% of the intake of control animals (CTL) for 21 days) benefits 1-year-old (CR1yr) and 2-year-old (CR2yr) Wistar rats, with regard to insulin secretion and action. Plasma insulin and the insulin secreted by isolated islets were measured with radioimmunoassay, and the insulin sensitivity of peripheral tissues was assessed with the intraperitoneal glucose tolerance test (IPGTT), intraperitoneal insulin tolerance test, and hepatic and muscle adenosine monophosphate-activated protein kinase (AMPK) phosphorylation measurements. Body weight, epididymal fat pad, epididymal fat pad/body weight index, plasma glucose, and insulin were lower in the CR1yr than in the control (CTL1yr) rats. Serum cholesterol, triglycerides, and protein, as well as hepatic and muscle glycogen content, were similar between the CR and CTL groups. The IPGTT was higher in CR2yr and CTL2yr rats than in CR1yr and CTL1yr rats, and insulin sensitivity was higher in CR1yr and CR2yr rats than in their respective CTLs. This was associated with an increase in hepatic and muscle AMPK phosphorylation. No differences in glucose-induced insulin secretion in the isolated islets were observed between CRs and their respective CTL rats. In conclusion, short-term calorie restriction provoked more severe alterations in CR1yr than CR2yr rats. The normoglycemia observed in both CR groups seems to be due to an increase in insulin sensitivity, with the involvement of liver and muscle AMPK.

Analysis of a sample of type 2 diabetic patients with obesity or overweight and at cardiovascular risk: a cross sectional study in Spain

Background

The multifactorial control of diabetes relies on interventions that provide patients with the best knowledge and resources available. The objective of this research was to analyze the clinical characteristics of a sample of people with type 2 diabetes at high cardiovascular risk, and establish possible links between disease control, family history and lifestyle, to improve the quality of interventions. Family history, lifestyle habits, blood pressure, anthropometric data and laboratory tests were analyzed in this descriptive and comparative cross-sectional study.

Results

All patients had a pathological body mass index (BMI), and in those patients with a family history of diabetes, the disease was more serious and onset was earlier. Overall, 70.9% were taking drugs for arterial blood pressure management, with mean values within recommended limits; 87.1% were taking antihyperlipidemic drugs and had mean values for blood lipids within reference range; 93.5% were receiving oral antidiabetic drugs and/or insulin and had blood glucose and glycosylated hemoglobin (HbA_1c) values higher than recommended limit; and 87% were taking antiplatelet drugs and had fibrinogen and ultrasensitive C-reactive protein higher than the normal range. High HbA_1c values were found in a high proportion of our sample who were not following a tailored diet (84.2%), and better BMIs were associated with moderate physical activity. Coexistence of somatic disorders (97.4% of the sample with musculoskeletal diseases) could lead to the lack of physical activity.

Conclusions

This sample of patients with type 2 diabetes and at high cardiovascular risk, had acceptable metabolic control, facilitated by drug therapy. Family history of diabetes was associated with earlier disease onset and worse disease progression. Patients who were not following a tailored diet had worse HbA_1c values compared with those who were. Individuals who practiced moderate physical activity in line with international recommendations for weight maintenance had the best BMI values, but the high prevalence of comorbidities could adversely affect exercise habits. Appropriate use of medication, dietary advice, and tailored physiotherapy physical activity suitable for people with comorbidities should be included in multifactorial treatment strategies for these patients, particularly in the presence of a family history of diabetes.

Acute caloric restriction improves glomerular filtration rate in patients with morbid obesity and type 2 diabetes

AIM

The role of caloric restriction in the improvement of renal function following bariatric surgery is still unclear; with some evidence showing that calorie restriction can reduce proteinuria. However, data on the impact of caloric restriction on renal function are still lacking.

METHODS

Renal function, as measured by glomerular filtration rate (GFR), was evaluated in 14 patients with type 2 diabetes mellitus, morbid obesity and stage 2 chronic kidney disease before and after a 7-day very low-calory diet (VLCD).

RESULTS

After the VLCD, both GFR and overall glucose disposal (M value) significantly increased from 72.6 ± 3.8 mL/min/1.73 m(-2) BSA to 86.9 ± 6.1 mL/min/1.73 m(-2) BSA (P=0.026) and from 979 ± 107 μmol/min(1)/m(2) BSA to 1205 ± 94 μmol/min(1)/m(2) BSA (P=0.008), respectively. A significant correlation was observed between the increase in GFR and the rise in M value (r=0.625, P=0.017).

CONCLUSION

Our observation of improved renal function following acute caloric restriction before weight loss became relevant suggesting that calory restriction per se is able to affect renal function.

Assessment of pancreatic β-cell function: review of methods and clinical applications

Type 2 diabetes mellitus (T2DM) is characterized by a progressive failure of pancreatic β-cell function (BCF) with insulin resistance. Once insulin over-secretion can no longer compensate for the degree of insulin resistance, hyperglycemia becomes clinically significant and deterioration of residual β-cell reserve accelerates. This pathophysiology has important therapeutic implications. Ideally, therapy should address the underlying pathology and should be started early along the spectrum of decreasing glucose tolerance in order to prevent or slow β-cell failure and reverse insulin resistance. The development of an optimal treatment strategy for each patient requires accurate diagnostic tools for evaluating the underlying state of glucose tolerance. This review focuses on the most widely used methods for measuring BCF within the context of insulin resistance and includes examples of their use in prediabetes and T2DM, with an emphasis on the most recent therapeutic options (dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists). Methods of BCF measurement include the homeostasis model assessment (HOMA); oral glucose tolerance tests, intravenous glucose tolerance tests (IVGTT), and meal tolerance tests; and the hyperglycemic clamp procedure. To provide a meaningful evaluation of BCF, it is necessary to interpret all observations within the context of insulin resistance. Therefore, this review also discusses methods utilized to quantitate insulin-dependent glucose metabolism, such as the IVGTT and the euglycemic-hyperinsulinemic clamp procedures. In addition, an example is presented of a mathematical modeling approach that can use data from BCF measurements to develop a better understanding of BCF behavior and the overall status of glucose tolerance.

Exaggerated glucagon-like peptide 1 response is important for improved β-cell function and glucose tolerance after Roux-en-Y gastric bypass in patients with type 2 diabetes

β-Cell function improves in patients with type 2 diabetes in response to an oral glucose stimulus after Roux-en-Y gastric bypass (RYGB) surgery. This has been linked to the exaggerated secretion of glucagon-like peptide 1 (GLP-1), but causality has not been established. The aim of this study was to investigate the role of GLP-1 in improving β-cell function and glucose tolerance and regulating glucagon release after RYGB using exendin(9-39) (Ex-9), a GLP-1 receptor (GLP-1R)-specific antagonist. Nine patients with type 2 diabetes were examined before and 1 week and 3 months after surgery. Each visit consisted of two experimental days, allowing a meal test with randomized infusion of saline or Ex-9. After RYGB, glucose tolerance improved, β-cell glucose sensitivity (β-GS) doubled, the GLP-1 response greatly increased, and glucagon secretion was augmented. GLP-1R blockade did not affect β-cell function or meal-induced glucagon release before the operation but did impair glucose tolerance. After RYGB, β-GS decreased to preoperative levels, glucagon secretion increased, and glucose tolerance was impaired by Ex-9 infusion. Thus, the exaggerated effect of GLP-1 after RYGB is of major importance for the improvement in β-cell function, control of glucagon release, and glucose tolerance in patients with type 2 diabetes.

Roux-en-Y gastric bypass vs sleeve gastrectomy for obese patients with type 2 diabetes: a randomised trial

AIMS/HYPOTHESIS

Bariatric surgery is gaining acceptance as a 'metabolic surgical intervention' for patients with type 2 diabetes. The optimal form of surgery and the mechanism of action of these procedures are much debated. We compared two bariatric procedures for obese patients with type 2 diabetes and evaluated their effects on HbA1c and glucose tolerance.

METHODS

We performed a parallel un-blinded randomised trial of Roux-en-Y gastric bypass (RYGB) vs sleeve gastrectomy (SG) in 41 obese patients with type 2 diabetes, who were bariatric surgery candidates attending the obesity clinic. HbA1c, body composition and glucose tolerance were evaluated at baseline, and at 3 and 12 months.

RESULTS

Of the 41 patients, 37 completed the follow-up (19 RYGB, 18 SG). Both groups had similar baseline anthropometric and biochemical measures, and showed comparable weight loss and fat:fat-free mass ratio changes at 12 months. A similar normalisation of HbA1c levels was observed as early as 3 months post-surgery (6.37 ± 0.71% vs 6.23 ± 0.69% for RYGB vs SG respectively, p < 0.001 in both groups for baseline vs follow-up).

CONCLUSIONS/INTERPRETATION

In this study, RYGB did not have a superior effect in comparison to SG with regard to HbA1c levels or weight loss during 12 months of follow-up.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00667706.

FUNDING

This work was supported by grant no. 3-000-8480 from the Israel Ministry of Health Chief Scientist, the Stephen Morse Diabetes Research Foundation and by Johnson & Johnson.

Preliminary evidence that obese patients with obstructive sleep apnea/hypopnea syndrome are refractory to the acute beneficial metabolic effects of a very low calorie diet

Since obesity seems to play a causal role in both obstructive sleep apnea/hypopnea syndrome (OSAHS) and type 2 diabetes, the question arises whether diet-induced weight loss is equally efficacious in type 2 diabetic patients with and without OSAHS. The present study was aimed to investigate the effect of 1 week very low calorie diet (VLCD) on oxygen desaturation index (ODI) and on glucose regulation in OSAHS versus non-OSAHS patients. Fourteen patients with type 2 diabetes mellitus and morbid obesity were enrolled. According to ODI, patients were divided into 2 groups (with and without OSAHS) and evaluated by a hyperglycemic clamp study, before and after a 7 day-VLCD. After a VLCD, a significant reduction of anthropometric parameters, in the overall group and in subgroups, was observed. M-value and acute insulin response increased significantly only in patients without obstructive sleep apnea (990.10 ± 170.19 vs. 1,205.22 ± 145.73 μmol min(-1) m(-2), p = 0.046; -1.05 ± 8.40 vs. 48.26 ± 11. 90 pmol/L, p = 0.028, respectively). The average 24-h heart rate (24-h HR) fell significantly (p = 0.05), primarily because of a decrease during daytime (p = 0.041), in the whole group. In conclusion, we observed that morbidly obese patients with type 2 diabetes and OSAHS are specifically resistant to the acute beneficial effects of VLCD on metabolic parameters. Our preliminary observation deserves further investigation to clarify the pathogenetic mechanisms involved.

β-Cell lipotoxicity in response to free fatty acid elevation in prepubertal youth: African American versus Caucasian contrast

Prepubertal African American (AA) youth compared with their Caucasian (C) peers have higher insulin secretion, which correlates positively with free fatty acid (FFA) concentration. In our continued efforts to explain the racial disparity in insulinemia, and because FFAs modulate insulin secretion, we hypothesized that AA youth would have a greater response to FFA-induced β-cell insulin secretion than C youth. We compared the short-term effects of FFA elevation on fasting and glucose-stimulated C-peptide-modeled insulin secretion in prepubertal normal-weight AA versus C peers during a 2-h hyperglycemic clamp (12.5 mmol/L) on two occasions: 1) infusion of normal saline and 2) infusion of 20% intralipid (IL). During IL infusion, insulin sensitivity (IS) declined comparably in AA and C youth. Glucose sensitivity of first- and second-phase insulin secretion showed a significant condition × race interaction being higher in AA youth. Disposition index, β-cell function relative to IS, declined with IL infusion in AA and C youth, with a significantly greater decrease in Cs compared with AAs. In conclusion, AA and C prepubertal youth both demonstrated a decline in β-cell function relative to IS during IL infusion, indicative of acute lipotoxicity. The greater decline in C youth compared with AAs may suggest that C youth are more susceptible to β-cell lipotoxicity than AA youth, or alternatively, that AA youth are hypersensitive to FFA stimulation of β-cell insulin secretion, consistent with our theory.

Metabolic and psychological response to 7-day fasting in obese patients with and without metabolic syndrome

BACKGROUND

Extended modified fasting is a frequently practiced tradition in Europe. It is claimed to improve the cardiometabolic state and physical and psychological well-being by an evolutionary co-developed adaptation response. We aimed to investigate the cardiometabolic and psychological effects of a 7-day fast and differences of these responses between patients with or without metabolic syndrome (MetS).

METHODS

We investigated 30 female subjects (49.0 ± 8.1 years, BMI 30.4 ± 6.7 kg/m(2)) with (n = 12) and without (n = 18) MetS. All subjects participated in a 7-day fast according to Buchinger with a nutritional energy intake of 300 kcal/day and stepwise reintroduction of solid food thereafter. Outcomes were assessed baseline and after fasting and included measures of metabolic and glucoregulatory control, adipokines as well as psychological well-being as assessed by Profile of Mood States (POMS) and Hospital Anxiety and Depression Scale (HADS).

RESULTS

Mean weight decreased from 85.4 ± 18.8 kg to 79.7 ± 18.2 kg accompanied by systolic/diastolic blood pressure (BP) reduction of -16.2 mm Hg (95% CI: -9.1; -23.3 mm Hg) and -6.0 mm Hg (95% CI: -1.8; -10.3 mm Hg), each p < 0.001 and p = 0.005. Fasting led to marked decreases of levels of LDL-cholesterol, leptin, and insulin and increases of levels of adiponectin, leptin receptors, and resistin. Fasting-induced mood enhancement was reflected by decreased anxiety, depression, fatigue, and improved vigor. Patients with MetS showed some greater changes in B P, LDL-cholesterol, triglycerides, adiponectin, leptin, and sleep quality. Fasting was well-tolerated.

CONCLUSIONS

Our results point to marked beneficial responses to 7-day modified fasting and a potential role in the prevention of the MetS. Randomized trials with longer observation periods should test the clinical effectiveness of fasting in metabolic diseases.

Beneficial effects of an 8-week, very low carbohydrate diet intervention on obese subjects

Aim. To investigate the effects of weight loss during an 8-week very low carbohydrate diet (VLCD) on improvement of metabolic parameters, adipose distribution and body composition, and insulin resistance and sensitivity in Chinese obese subjects. Methods. Fifty-three healthy obese volunteers were given an 8-week VLCD. The outcomes were changes in anthropometry, body composition, metabolic profile, abdominal fat distribution, liver fat percent (LFP), and insulin resistance and sensitivity. Results. A total of 46 (86.8%) obese subjects completed the study. The VLCD caused a weight loss of −8.7 ± 0.6 kg (mean ± standard error (SE), P < 0.0001) combined with a significant improvement of metabolic profile. In both male and female, nonesterified fatty acid (NEFA) significantly decreased (−166.2 ± 47.6 μmol/L, P = 0.001) and β-hydroxybutyric acid (BHA) increased (0.15 ± 0.06 mmol/L, P = 0.004) after eight weeks of VLCD intervention. The significant reductions in subcutaneous fat area (SFA), visceral fat area (VFA), and LFP were −66.5 ± 7.9 cm², −35.3 ± 3.9 cm², and −16.4 ± 2.4%, respectively (all P values P < 0.0001). HOMA IR and HOMA β significantly decreased while whole body insulin sensitivity index (WBISI) increased (all P values P < 0.001). Conclusion. Eight weeks of VLCD was an effective intervention in obese subjects. These beneficial effects may be associated with enhanced hepatic and whole-body lipolysis and oxidation.

Alcohol use behaviors, fat intake and the function of pancreatic β-cells in non-obese, healthy Korean males: findings from 2010 Korea National Health and Nutrition Examination Survey

AIMS

In the present study, we aimed to identify dietary factors related to insulin secretion function especially in healthy, non-obese Korean males.

METHODS

Data were obtained from the Korea National Health and Nutrition Examination Survey V-1 (KNHANES V-1). Nine hundred and twenty male adults aged >30 years of normal weight were included, excluding those with type 2 diabetes mellitus and liver disease. Alcohol use disorders identification test (AUDIT) score which represents alcohol use behaviors and nutrient intakes was used, and homeostasis model assessment of β-cell function (HOMA-B score) was calculated.

RESULTS

HOMA-B score was associated with age (p < 0.001), AUDIT score (p = 0.030), and percentage of fat from total energy intake (p = 0.002). HOMA-B scores in the problematic AUDIT group were significantly lower than those in the normal AUDIT group. In addition, HOMA-B scores in the lowest fat intake group were significantly lower than those in the medium fat intake group, but similar to those in the highest fat intake group. There was an interaction between alcohol use behaviors and percentage of fat from energy intake in determining HOMA-B score (p for interaction = 0.034).

CONCLUSIONS

Alcohol use behaviors and percentage of fat from energy intake were found to be associated with HOMA-B score in healthy, non-obese Korean males.

Neural stem cells in the diabetic brain

Experimental diabetes in rodents rapidly affects the neurogenic niches of the adult brain. Moreover, behavioral disorders suggest that a similar dysfunction of the neurogenic niches most likely affects diabetic and prediabetic patients. Here, we review our present knowledge about adult neural stem cells, the methods used for their study in diabetic models, and the effects of experimental diabetes. Variations in diet and even a short hyperglycemia profoundly change the structure and the proliferative dynamics of the neurogenic niches. Moreover, alterations of diabetic neurogenic niches appear to be associated with diabetic cognitive disorders. Available evidence supports the hypothesis that, in the adult, early changes of the neurogenic niches might enhance development of the diabetic disease.