Studies of Insulin and Glucagon Action in the Liver (SIGNAL)

Duke University

Status and phase: Begins enrollment in 1 month; Phase 2; Phase 1

Conditions: Diabetes (DM)

Treatments: Drug: Saline (placebo); Drug: Glucagon

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT07300982

Pro00117291

R01DK141090 (U.S. NIH Grant/Contract)

Details and patient eligibility

About

This study examines how glucagon works to regulate glucose metabolism, based on new findings that suggest glucagon signaling in the liver has more than one role, and that these multiple roles can be opposing in nature. Understanding this biology provides an opportunity to develop new generations of glucagon-based drugs that target specific pathways, making them more effective at controlling blood glucose.

Participants will complete paired, 5-hour hyperinsulinemic glucose clamp visits in which they receive either glucagon or saline infusions while blood glucose is maintained and frequent blood samples are collected. The primary focus is whether coordinated glucagon and insulin signaling enhances hepatic insulin sensitivity.

Full description

Volunteers will undergo screening for medical history, medication usage, and blood work; those who qualify will be offered participation. Study participation will last approximately 5-12 weeks depending on appointment availability and the number of infusions planned. This protocol involves two sets of paired procedures. Approximately 15 participants will complete each set of paired visits. Participants can opt to complete one set of paired visits or both sets of paired visits.

Set 1: Each participant will complete two 5-hour hyperinsulinemic clamp procedures to examine the effects of glucagon on glucose metabolism while measuring systemic glucose turnover and related blood markers. The procedures will be identical, except for the final phase of the procedure when either saline or a stepwise glucagon infusion will be administered.

Set 2: Each participant will complete two 5-hour hyperinsulinemic clamp procedures to examine the effects of insulin on glucose metabolism while measuring systemic glucose turnover and related blood markers. The procedures will be identical, except for the final phase of the procedure when either saline or a steady glucagon infusion will be administered.

Enrollment: 40 estimated patients

Sex: All

Ages: 18 to 45 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Healthy adults age 18-45 years
• Body Mass Index (BMI) < 27.0 kg/m²
• Fasting plasma glucose ≤ 95 mg/dL or HbA1c ≤ 5.8% as measured at screening visit

Exclusion criteria

• Active medical disease: e.g. active infectious, inflammatory, neurodegenerative or mental health disorders
• No personal history of diabetes or pancreatitis
• No personal history of cardiac, gastrointestinal, renal or liver disease
• No history of diabetes among any first-degree family members
• Renal insufficiency (eGFR < 60 mL/kg/min)
• Anemia (hematocrit < 34%) as measured at screening visit
• Pregnant females
• Consumption of daily medications that alter glucose metabolism of GI function (glucocorticoids, psychotropics, narcotics, metoclopramide)

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

---

40 participants in 2 patient groups, including a placebo group

Glucagon infusion during hyperinsulinemic clamp

Experimental group

Description:

Glucagon infusion either graded (0.2→0.4→0.6 ng/kg/min) or continuous (0.4 ng/kg/min) during the final 90 minutes of a hyperinsulinemic glucose clamp. The graded or continuous glucagon infusions are given as a component of 2 separate protocols.

Treatment:

Drug: Glucagon

Saline infusion during hyperinsulinemic clamp

Placebo Comparator group

Description:

Saline infusion during the final 90 minutes of an otherwise identical clamp procedure.

Treatment:

Drug: Saline (placebo)