Adrian Vella, M.D.

This study aims to identify an early stage biomarker for type 1 diabetes. In vitro evidence identified a significant enrichment of the chemokine CXCL10 in β-cell derived EXO upon exposure to diabetogenic pro-inflammatory cytokines. The study also aims to test protocols for efficient isolation of plasma-derived EXO from small volumes of sample, develop an assay for the sensitive detection of CXCL10 in plasma-derived EXO, and characterization of plasma-derived EXO through assessment of concentration, size, and content (proteomics).

Determine the effect of endocrine pancreas morphology, turnover and dedifferentiation on glucose tolerance in humans. 

The purpose of this study is to establish how glucagon and insulin interact with their receptors to control fasting glucose in health and in prediabetes.

The purpose of this study is to establish how glucagon and insulin interact with their receptors to control fasting glucose in health and in prediabetes.

The purpose of this study is to Estimation of metabolic parameters related to meal-absorption, insulin secretion and sensitivity, lactate production, glucagon secretion, glucose production, peripheral uptake and effectiveness during a standard-mixed meal. Estimation of changes to metabolic parameters during bouts of moderate and high-intensity physical activity. Estimate meal absorption for real-life meals, explicitly accounting for the macronutrient content of each meal. Develop meal macronutrient estimation algorithms based on CGM + CLM + Activity Tracker. Evaluate the feasibility of automated meal logging and analysis algorithms. 

The purpose of this study evaluates a subset of people with isolated Impaired Fasting Glucose with Normal Glucose Tolerance (i.e., IFG/NGT) believed to have normal β-cell function in response to a glucose challenge, suggesting that – at least in this subset of prediabetes – fasting glucose is regulated independently of glucose in the postprandial period. To some extent this is borne out by genetic association studies which have identified loci that affect fasting glucose but not glucose tolerance and vice-versa.

The purpose of this study is determine the effect of β-cell function and glycemic control on islet GLP-1.

The purpose of this study is to determine the contribution of islet GLP-1 to islet function in people with and without diabetes-associated genetic variation in TCF7L2 (rs7903146).

The purpose of this study is to measure hepatic extraction of amino acid (AA) in response to physiologic post-prandial concentrations of glucagon. In addition to changes in essential AA, we will also measure the extraction of other AAs, and their metabolites, across the liver. While measuring the effect of glucagon on AA metabolism, we will also examine how EGP and hepatic lipid metabolism respond to these conditions. While early reports have focused on hepatic steatosis, we will ascertain if its presence is necessary to alter glucagon’s actions on hepatic

The purpose of this study is to determine the contribution of islet GLP-1 to islet function in prediabetes.

The purpose of this study is to determine if glucose fluctuations correlate with islet function in prediabetes.

The purpose of this study is to evaluate the role of GLP1R in the response to elevated  glucagon concentrations.

The GLP-1 receptor gene is found on the beta cells of the pancreas. Its role is in the control of blood sugar level by enhancing insulin secretion from the pancreas after eating a meal. Results from this study may help us identify therapeutic pathways to prevent or reverse type 2 diabetes mellitus.

The purpose of the study is to examine the effect of different dosages of Exendin on glucose metabolism, glucagon and insulin secretion, and on insulin action.

The purpose of this study is to examine the effect of Ghrelin on the regulation of food intake and sensation of fullness after bariatric surgery.

The purpose of this study is to evaluate the efficacy of pasireotide s.c. on level 2 hypoglycaemic events after a mixed meal tolerance test (MMTT) in patients with Post-Bariatric Hypoglycaemia (PBH) after 12 weeks of treatment.

Multi-center, phase II study evaluating efficacy, safety and pharmacokinetics of pasireotide in patients with dumping syndrome.  

The purpose of this study is to determine if changes in fasting glucose and FFA concentrations alter 1st phase insulin secretion and proinsulin secretion in non-diabetic and pre-diabetic humans.
 

The purpose of this study is to determine the effect of diabetes-associated variation in TCF7L2 on insulin synthesis and on insulin secretion.

The purpose of this study is to evaluate if breathing pure oxygen overnight affects insulin sensitivity in participants with diabetes. 
 

The purpose of this study is to determine the mechanism(s) by which common bariatric surgical procedures alter carbohydrate metabolism. Understanding these mechanisms may ultimately lead to the development of new interventions for the prevention and treatment of type 2 diabetes and obesity.

The purpose of this study is to determine the mechanism(s) underlying symptoms of hypoglycemia that are experienced by patients after auto-islet transplantation.

The purpose of this study is to determine the effect of duration of exendin-9,39 infusion on insulin secretion.

The purpose of this study is to determine if changes in fasting glucose and fasting free fatty acids (FFA) concentrations alter postprandial glucose metabolism in non-diabetic and pre-diabetic humans.

The purpose of this research is to find out how genetic variations in GLP1R, alters insulin secretion, in the fasting state and when blood sugars levels are elevated. Results from this study may help us identify therapies to prevent or reverse type 2 diabetes mellitus.

Observational studies suggest that bariatric surgery is the most effective intervention for weight loss. Comparative effectiveness of Roux-en-Y Gastric Bypass (RYGB) and Sleeve Gastrectomy (SG) demonstrate that RYGB is significantly superior to SG in terms of weight loss and glycemic control. Both RYGB and SG increase GLP-1 concentrations which directly affect B-cell function. Data has shown that the postprandial rise in GLP-1 might affect feeding behavior after RYGB and to a lesser extent SG, where the increase in GLP-1 is less marked. In this study the investigators propose to randomize subjects undergoing SG to receive either placebo or Liraglutide, a GLP-1 receptor agonist, to compare weight loss and CV risk factors.

The purpose of this study is to use the well-characterized Diabetes Control and Complications Trial (DCCT) cohort of 1,400 patients to determine the long-term effects of prior separation of glycemic levels on micro- and macrovascular outcomes.

The purpose of this study is to identify novel genetic variants that predispose to Type 1 Diabetes.

The purpose of this study is to determine how amino acids alter the suppression of α-cell secretion by glucose.

The goal of this study is to determine the role of postprandial glucagon suppression and insulin secretion in the progression of glucose intolerance in people with diabetes-associated variation in TCF7L2.

The purpose of this study is to determine the changes in tissue function that occur in the first year postpartum in women with and without gestational diabetes mellitus.

The purpose of this study is to determine if the set-point for fasting insulin secretion, and the subsequent response to hyperglycemia, is altered in people with IFG with or without accompanying IGT.

The purpose of this study is to determine if you have the ability to secrete any measurable level of insulin. You will be asked to undergo a standard test called the Mixed Meal Tolerance Test (MMTT). The MMTT stimulates your body to secrete insulin. The C-peptide levels (amount of insulin that your body makes) will then be measured. A similar test was conducted when you were evaluated for enrollment into the DCCT. We want to see if that has changed some 25-30 years later.

This study will test the efficacy of BKR-017 (colon-targeted 500 mg butyrate tablets) on insulin sensitivity, glucose control and triglycerides in type-1 diabetes subjects.

The study is being undertaken to understand how a gastric bypass can affect a subject's diabetes even prior to their losing significant amounts of weight. The hypothesis of this study is that increased glucagon-like peptide-1 (GLP-1) secretion explains the amelioration in insulin secretion after Roux-en-Y Gastric Bypass (RYGB) surgery.

The purpose of this study is to determine the metabolic effects of Colesevelam, particularly for the ability to lower blood sugar after a meal in type 2 diabetics, in order to develop a better understanding of it's potential role in the treatment of obesity.

The experimental design we propose will enable the dissection of the relative contribution of insulin and glucagon concentrations to endogenous glucose production. Acquisition of this data will allow us to develop a model of insulin and glucagon contributions to postprandial glucose metabolism

The purpose of this study is to determine how common bariatric surgical procedures alter carbohydrate metabolism by examining the effect of vagal nerve stimulation on insulin secretion and action.

The purpose of this study is to determine how caloric restriction alters hepatic glucagon action

Elevated fasting AA concentrations are associated with T2DM risk. In addition, hepatic steatosis has been associated with an impaired ability of glucagon to stimulate hepatic clearance of AAs. We and others have shown that caloric restriction lowers fasting glucose, EGP and glucagon. However, the effects on these parameters in the postprandial period are unclear. This study examine if prior observations can and to what degree, be explained by improved hepatic glucagon action. Because caloric restriction decreases hepatic fat content the experiment will also determine if a reduction in hepatic fat content is associated with changes in glucagon’s effects on hepatic AA, glucose, and lipid metabolism. 

The purpose of this study is to determine the longitudinal effect of diabetes-associated variation in TCF7L2 on a-cell function and the contribution of a-cell function to longitudinal glucose tolerance and EGP in non-diabetic subjects.  

The purpose of this study is to determine the effect of endogenous GLP-1 secretion on islet function in people with Typr 2 Diabetes Mellitus (T2DM).

GLP-1 is a hormone made by the body that promotes the production of insulin in response to eating. However, there is increasing evidence that this hormone might help support the body’s ability to produce insulin when diabetes develops.