Physiologic Response to Glucagon at Varying Insulin Levels
The purpose of this research study is to test how different levels of insulin block the effect of glucagon. Insulin is a hormone that lowers blood glucose. Glucagon raises blood glucose. Both are natural hormones made by people without diabetes. Sensor-based blood glucose control studies have been done by our research group using glucagon in small doses to prevent hypoglycemia (low blood sugar). However, sometimes glucagon does not work to raise blood sugar. The investigators believe this is because of too much insulin in the body. This study will help determine how different levels of insulin in the body affect the ability of glucagon to raise blood sugar.
|Study Design:||Endpoint Classification: Pharmacodynamics Study
Intervention Model: Single Group Assignment
Masking: Single Blind (Subject)
Primary Purpose: Basic Science
|Official Title:||The Hepatic Glucose Response to Glucagon at Varying Insulin Levels: Implications for Closed Loop Glycemic Control.|
- Area under the curve for glucose above baseline [ Time Frame: 60 minutes after each glucagon administration ] [ Designated as safety issue: No ]The change in the rate of glucose appearance will be assessed by measuring the stable glucose isotope (dideuterated glucose, D2) using a gas chromatography-mass spectrometry assay.
- Peak glucose value above baseline [ Time Frame: 60 minutes post glucagon administration ] [ Designated as safety issue: No ]Venous blood glucose values will be assessed with the Hemocue Glucose 201 Analyzer.
|Study Start Date:||November 2011|
|Study Completion Date:||March 2013|
|Primary Completion Date:||March 2013 (Final data collection date for primary outcome measure)|
We investigators have been working on the development of a closed loop (artificial endocrine pancreas) insulin and glucagon infusion system since 2005 and are part of the Juvenile Diabetes Research Foundation Artificial Pancreas Consortium. As part of our studies, we give small doses of glucagon to prevent hypoglycemia. As we assessed the success and failure of glucagon administration during these studies, we found the use of glucagon reduced the frequency of hypoglycemia by about 75%. However, the fact that approximately 25% of administrations of glucagon are ineffective remains a concern.
The primary question to be addressed by this study is, in the setting of low dose subcutaneous glucagon administration, how do plasma glucagon and plasma insulin quantitatively interact? In other words, as the rate of insulin administration is increased, how much more glucagon is necessary to overcome the effect of insulin to prevent hypoglycemia? This study is designed to address this question. Subjects will be brought in to a Legacy Hospital for four 10 hour experiments on each of four separate days. On each study day, there will be a continuous infusion of a different rate of IV Regular insulin in order to achieve different steady state free insulin levels. At each insulin level, there will be four subcutaneous glucagon doses given. Octreotide will be infused by IV at a constant rate to suppress endogenous production of glucagon. A stable glucose isotope will also be infused to allow for measurement of hepatic glucose production and glucose turnover. Arterialized venous blood glucose will be measured by the HemoCue Glucose 201 Analyzer.
|United States, Oregon|
|Legacy Health System|
|Portland, Oregon, United States, 97210|
|Principal Investigator:||W Kenneth Ward, MD||Legacy Health System|