Novel Approach for the Prevention of Hypoglycemia Associated Autonomic Failure (HAAF)

The overall goal of this study is to develop a new and practical way to prevent the development of Hypoglycemia Associated Autonomic Failure (HAAF), which is unawareness of hypoglycemia (low blood sugar) in individuals with diabetes. Previous studies suggest that two medications, naloxone and diazoxide, may increase the body's ability to respond to episodes of low blood sugar and prevent the development of HAAF (or hypoglycemia unawareness). Only healthy subjects are being recruited for this study. The study has three distinct phases. In the first phase, healthy, non-diabetic individuals who are susceptible to developing HAAF are identified. Only these individuals will be studied in the second and third phases. The second phase of this study evaluates the effect of using a naloxone nasal spray versus a placebo nasal spray in improving the body's response to episodes of low blood sugar and in preventing the development of HAAF. The third phase of this study evaluates the effect of using naloxone nasal spray and diazoxide in combination, compared to naloxone nasal spray plus a placebo (for diazoxide) or diazoxide plus a placebo (for naloxone) in improving the body's response to episodes of low blood sugar and in preventing the development of HAAF.

Type I diabetes affects the body's ability to respond to low blood sugar (hypoglycemia). Repeated episodes of hypoglycemia may affect an individual's autonomic system, and leads to Hypoglycemia Associated Autonomic Failure (HAAF) in around two-thirds of individuals. This study is looking at healthy, non-diabetic individuals who are susceptible to developing HAAF and their response to either naloxone nasal spray alone or in combination with diazoxide in improving their body's ability to respond to episodes of low blood sugar, and in preventing the development of HAAF. The body's response to episodes of hypoglycemia is measured using a procedure called a hypoglycemic clamp. Each phase of this study involves three clamp procedures over a period of 2 days. During the clamp procedures, glucose (a sugar) and insulin (a hormone produced in the pancreas that regulates the amount of glucose in the blood) are infused with an intravenous catheter, and blood samples are collected periodically throughout the procedure to measure blood sugar levels and the levels of several hormones, including epinephrine, that are found in the body and are related to glucose metabolism. The rates of endogenous glucose production (a measure of the body's production of sugar) will be measured. Additionally, the level of awareness of hypoglycemia symptoms will be monitored using a standardized questionnaire. Both hypoglycemia and stress activate the body's opioid system. Recently published data has shown that blocking opioid receptors with naloxone may increase the body's ability to respond to hypoglycemia.The body's response to hypoglycemia affects many systems, and acting on several of these systems may help the body to respond more effectively to episodes of low blood sugar, and to prevent the development of HAAF. Studies have shown that potassium channels in the hypothalamus, a part of the brain, have an important role in detecting hypoglycemia. Diazoxide activates potassium channels in the cells of the brain that respond to changes in sugar (glucose) that occur in the body, and may also reduce the development of hypoglycemia associated autonomic failure. Additionally, certain glucose-responsive cells in the brain have opioid receptors that are combined with potassium channels which may respond to both diazoxide and naloxone which may work together to more effectively increase the body's ability to respond to episodes of low blood sugar and prevent HAAF. UPDATE: This study was terminated early and only the second phase (Aim 2) of the study above was conducted. This phase was designed to assess the effect of opioid receptor antagonist - intranasal naloxone - as compared to matched placebo on experimentally induced HAAF in healthy, nondiabetic volunteers.