Effects of HBO on Glucose in Patients With DM

Brief Summary

The purpose of this Research Study is: 1. To determine the reliability and performance of the Dexcom G6® continuous glucose monitoring (CGM) system in patients with diabetes undergoing hyperbaric oxygen (HBO2) exposure. The study-specific blood glucose meter and CGM system are approved by the FDA (U.S. Food and Drug Administration). 2. To determine whether HBO2 exposure causes blood glucose to drop as a result of the treatment. 3. To determine whether HBO2 causes a change in blood glucagon (a hormone that raises blood glucose). Investigators will be comparing changes in blood glucose and glucagon in volunteers with diabetes who will be exposed to a single hyperbaric oxygen treatment (pressurization to 2.4 atmospheres absolute for 90 minutes) to a control period of 2 hours where volunteers will simulate a hyperbaric treatment while sitting in an examination room breathing room air at sea level pressure. Investigators will be measuring blood glucose with a variety of devices including a continuous glucose monitor, two point-of-care glucometers, and the hospital inpatient laboratory measurement of venous blood.