Inspiratory Muscle Strength Training in Adults With Type 1 Diabetes

Adults with type 1 diabetes have elevated cardiovascular disease risk, and systolic blood pressure is a leading modifiable contributor to that risk. Aerobic exercise lowers blood pressure but poses time and glycemic-management barriers for people with type 1 diabetes. Inspiratory muscle strength training is a brief, home-based, device-based intervention that takes about five minutes per day and has lowered systolic blood pressure in other adult populations. This pilot trial will test whether eight weeks of daily high-resistance inspiratory muscle strength training lowers blood pressure and improves vascular function in adults with type 1 diabetes. Participants will be randomized 2:1 to high-resistance or very-low-resistance sham training using a POWERbreathe K3 device and will complete 30 training breaths per day at home for eight weeks. Outcomes are assessed before and after the training period.

Inclusion Criteria: * Age 18 to 35 years * Type 1 diabetes diagnosed more than 1 year before screening * Hemoglobin A1c (HbA1c) 10.0% or less within the last 3 months (may be measured at screening)- Body mass index 18 to 29.9 kg/m\^2 * Stable insulin delivery method for the past 30 days * Ability to read all device instructions and insulin pump settings * Estimated glomerular filtration rate at least 60 mL/min/1.73 m\^2 within the last 3 months (may be measured at screening) * Use of an insulin pump or insulin delivery by multiple daily injections * Attendance at 3 or more diabetes care visits over the past 12 months Exclusion Criteria: * Diabetes-related hospitalization, including for diabetic ketoacidosis or severe hypoglycemia, within 12 months of screening * Poorly controlled hypertension, defined as systolic blood pressure at least 140 mmHg or diastolic blood pressure at least 90 mmHg * Taking diabetes medications other than insulin * Structured exercise more than 150 minutes per week for the last 3 months * Pregnant, lactating, or planning to become pregnant within the study period * Unstable weight, defined as more than 5% change in the last 3 months * Significant organ system dysfunction, such as severe pulmonary, renal, hepatic, or cardiovascular disease * Diagnosed anemia or known hemoglobin less than 10 g/dL * Diagnosed neuropathic or psychiatric illness * Active nicotine or illegal drug use * Alcohol consumption totaling more than 10 standard drinks per week * Unable to grant voluntary informed consent * Unable or unwilling to follow the study protocol * Per the POWERbreathe device user manual: history of spontaneous pneumothorax; a collapsed lung that has not fully healed; a pacemaker or medical implant containing magnets or electronics; any condition of the eardrum, such as a burst eardrum that has not fully healed