Role of Alpha-to-beta Cell Communication to Adapt Insulin Secretion to Insulin Resistance.

Official title

Alpha to Beta Cell Communication in Health and Disease

Overview

Glucagon secretion from α-cells has long been viewed as primarily a counterregulatory mechanism - e.g. an agent with a role to prevent blood sugar from decreasing to levels that compromise function. Our group, along with other researchers, have begun to identify a much more complex role for α-cells, raising questions about when and how glucagon may influence blood glucose levels. This proposal looks to detail proglucagon peptide secretion from α-cells and the impact this has on β-cell function and glucose tolerance, in preclinical studies of human islets and translational studies in human subjects. This protocol registration describes Aim 2 from this NIH grant which involves 2 study populations and separate protocols but addresses a common question. Aim 3 in the grant is focused on a separate hypothesis and will be conducted and published separately from Aim 2.

Detailed description

Subjects will undergo screening for medical history, medication usage, and blood work; those who qualify will be offered participation. Study participation will last approximately 4-5 weeks depending on appointment availability.

Aim 2A: Each participant will have two 5-hour hyperglycemic clamp procedures to test the effect of fasting glucagon-like peptide 1 (GLP-1) action before and after experimental insulin resistance. The effect of endogenous proglucagon peptides (glucagon and GLP-1) to stimulate insulin secretion will be determined by blockade of the GLP-1 receptor with the antagonist exendin-9 (Ex-9) during glucose infusions. Insulin secretion experiments will be repeated before and after induction of insulin resistance. To induce insulin resistance, subjects will take dexamethasone, a synthetic glucocorticoid that has been shown in published studies and in a pilot study by our group to reduce insulin sensitivity by \~30%.

Aim 2B: This study will recruit non-diabetic subjects with obesity. They will be studied on two occasions using a 4.5-hour procedure with a hyperglycemic clamp to measure insulin secretion, followed by a hyperinsulinemic, euglycemic clamp to measure insulin sensitivity. This procedure will be done 2 times, once with saline infused during hyperglycemia as a control, and once with exendin-9 given during hyperglycemia to determine the role of GLP-1 receptor action.

Interventions

• Drug Exendin-9 is a 30 amino acid peptide that is an established competitive antagonist of the GLP-1 receptor. Subjects will receive exendin-9 by intravenous infusion at a rate of 600 pmol/kg/min
  Subjects in Aim 2A will receive exendin-9 on both experimental days and dexamethasone for one week before their second experimental day. Subjects in Aim 2B will receive exendin-9 on one of their two experimental days.
• Drug Dexamethasone
  Dexamethasone 6 mg daily

Primary outcome measures

• Insulin secretion [Time frame: Insulin secretion rates will be measured on both days of study in subjects participating in Aims 2A and 2B. Studies will be completed over a period of 4-5 weeks]
• Insulin secretion with and without exendin-9: Aims 2A and 2B [Time frame: 4-5 weeks]

Secondary outcome measures (1)

• Insulin sensitivity: Aim 2B [Time frame: Insulin sensitivity will be measured in subjects participating in Aim 2B during the hyperinsulinemic clamp in each of the two days of study. The two experiments will be completed in a 4-5 week period.]

Eligibility criteria

Aim 2A: Inclusion Criteria:

• Age 18-45
• Body Mass Index (BMI) < 27.0
• Fasting plasma glucose of ≤ 95 mg/dL or HbA1c value ≤ 5.8% as measured at screening visit

Exclusion criteria

• Active medical disease: e.g. active infectious, inflammatory, neurodegenerative or mental health disorders
• Personal history of diabetes or pancreatitis
• Personal history of cardiac, gastrointestinal, renal or liver disease
• Immediate family history of diabetes
• Renal insufficiency (eGFR < 60 mL/kg/min)
• Anemia (hematocrit < 34%) as measured at screening visit
• Pregnant females
• Poor vein access
• Consumption of daily medications that alter glucose metabolism of GI function (glucocorticoids, psychotropics, narcotics, metoclopramide)
• Apparent sensitivity to the study peptide as determined by the skin test

Aim 2B: Inclusion Criteria:

• Age 35-60
• Body Mass Index (BMI) ≥ 27.0
• Fasting plasma glucose of < 126 mg/dL or HbA1c value < 6.5% as measured at screening visit

Exclusion criteria

• Active medical disease: e.g. active infectious, inflammatory, neurodegenerative or mental health disorders
• Personal history of diabetes or pancreatitis
• Personal history of cardiac, gastrointestinal, renal or liver disease
• Immediate family history of diabetes
• Renal insufficiency (eGFR < 60 mL/kg/min)
• AST and/or ALT levels > 3x the upper limit of the normal range
• Anemia (hematocrit < 34%) as measured at screening visit
• Pregnant females
• Poor vein access
• Consumption of daily medications that alter glucose metabolism of GI function (glucocorticoids, psychotropics, narcotics, metoclopramide)
• Apparent sensitivity to the study peptide as determined by the skin test

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Single blind

Primary purpose

Basic science

Study locations

United States · 1 center

• Duke Center for Living — Durham

Publications

• Ryan AS, Muller DC, Elahi D. Sequential hyperglycemic-euglycemic clamp to assess beta-cell and peripheral tissue: studies in female athletes. J Appl Physiol (1985). 2001 Aug;91(2):872-81. doi: 10.1152/jappl.2001.91.2.872. PMID 11457805
• Jensen DH, Aaboe K, Henriksen JE, Volund A, Holst JJ, Madsbad S, Krarup T. Steroid-induced insulin resistance and impaired glucose tolerance are both associated with a progressive decline of incretin effect in first-degree relatives of patients with type 2 diabetes. Diabetologia. 2012 May;55(5):1406-16. doi: 10.1007/s00125-012-2459-7. PMID 22286551
• Salehi M, Vahl TP, D'Alessio DA. Regulation of islet hormone release and gastric emptying by endogenous glucagon-like peptide 1 after glucose ingestion. J Clin Endocrinol Metab. 2008 Dec;93(12):4909-16. doi: 10.1210/jc.2008-0605. Epub 2008 Sep 30. PMID 18827000
• Gray SM, Goonatilleke E, Emrick MA, Becker JO, Hoofnagle AN, Stefanovski D, He W, Zhang G, Tong J, Campbell J, D'Alessio DA. High Doses of Exogenous Glucagon Stimulate Insulin Secretion and Reduce Insulin Clearance in Healthy Humans. Diabetes. 2024 Mar 1;73(3):412-425. doi: 10.2337/db23-0201. PMID 38015721
• Schirra J, Sturm K, Leicht P, Arnold R, Goke B, Katschinski M. Exendin(9-39)amide is an antagonist of glucagon-like peptide-1(7-36)amide in humans. J Clin Invest. 1998 Apr 1;101(7):1421-30. doi: 10.1172/JCI1349. PMID 9525985
• Salehi M, Aulinger B, Prigeon RL, D'Alessio DA. Effect of endogenous GLP-1 on insulin secretion in type 2 diabetes. Diabetes. 2010 Jun;59(6):1330-7. doi: 10.2337/db09-1253. Epub 2010 Mar 9. PMID 20215429

Identifiers

NCT: NCT07224334 · Pro00116631 · R01DK142423

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗