Inspiratory Muscle Strength Training in Adults With Type 1 Diabetes

Time-Efficient Inspiratory Muscle Strength Training as a New Approach to Improve Cardiovascular Function Among 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.

Study Overview

• Status: Not yet recruiting
• Conditions: Type 1 Diabetes
• Intervention / Treatment: Device: High-Resistance Inspiratory Muscle Strength Training; Device: Sham Inspiratory Muscle Strength Training

Detailed Description

Approximately two million Americans live with type 1 diabetes, and cardiovascular disease is the leading cause of death in this population. After glycemic control, systolic blood pressure is the leading modifiable cardiovascular risk factor. Traditional aerobic exercise lowers blood pressure and improves vascular function, but most adults with type 1 diabetes do not meet physical activity recommendations, citing time constraints and concern about exercise-associated hypoglycemia.

Inspiratory muscle strength training (IMST) requires about five minutes per day, is performed seated at home with a commercially available handheld device, and is unlikely to provoke hypoglycemia. A retrospective analysis of five independent trials in 128 adults reported a 9 mmHg reduction in casual systolic blood pressure following high-resistance IMST compared with sham training, with effects that appear consistent across age, sex, health status, and baseline blood pressure. No study has examined IMST in people with type 1 diabetes.

Participants are randomized in a 2:1 ratio to high-resistance IMST or very-low-resistance sham IMST. Randomization uses a computer-generated sequence held by an unmasked team member who is responsible only for setting device resistance; participants, investigators, and outcome assessors remain masked to group assignment. All participants complete approximately 56 daily training sessions over eight weeks, each consisting of five bouts of six forceful inhalations with about 30 seconds of rest between bouts.

Maximal inspiratory pressure is measured at weeks 0, 2, 4, 6, and 8. For the high-resistance group, device resistance is set to a graded percentage of the participant's current maximal inspiratory pressure: 55% during weeks 1-2, 65% during weeks 3-4, and 75% during weeks 5-8. The sham group trains at 15% of maximal inspiratory pressure throughout. Participants are debriefed on their group assignment at the end of the post-training visit.

Testing visits at week 0 and week 8 include laboratory blood pressure, brachial artery flow-mediated dilation and post-occlusion reactive hyperemia by high-resolution ultrasound, central blood pressure and arterial stiffness by applanation tonometry, and isometric handgrip exercise testing with post-exercise circulatory occlusion. Participants measure their blood pressure at home once weekly on a provided automated monitor during weeks without a laboratory visit. Brief check-in contacts occur on odd weeks and device adjustment visits on even weeks. An optional follow-up visit repeating all assessments is offered at week 12.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jonathan Hoch; Phone Number: 8506441281; Email: chhs-cap@fsu.edu

Study Locations

• United States
  • Florida
    • Tallahassee, Florida, United States, 32306
      • Florida State University
    • Tallahassee, Florida, United States, 32306
      • Cardiovascular and Applied Physiology Laboratory
      • Contact: Joseph Watso, PhD; Phone Number: 8506441281; Email: jwatso@fsu.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High-Resistance Inspiratory Muscle Strength Training; Participants complete daily inspiratory muscle strength training using a POWERbreathe K3 device for eight weeks. Each session consists of five bouts of six forceful inhalations against resistance, with approximately 30 seconds of rest between bouts, for 30 training breaths per day. Resistance is set to a graded percentage of the participant's current maximal inspiratory pressure: 55% during weeks 1-2, 65% during weeks 3-4, and 75% during weeks 5-8.	Device: High-Resistance Inspiratory Muscle Strength Training; Daily home-based inspiratory muscle strength training using a POWERbreathe K3 device for eight weeks, at 55% of maximal inspiratory pressure during weeks 1-2, 65% during weeks 3-4, and 75% during weeks 5-8. Maximal inspiratory pressure is re-measured at weeks 0, 2, 4, 6, and 8 and resistance is adjusted accordingly.
Sham Comparator: Sham Inspiratory Muscle Strength Training; Participants complete daily inspiratory muscle strength training using a POWERbreathe K3 device for eight weeks. Each session consists of five bouts of six forceful inhalations against resistance, with approximately 30 seconds of rest between bouts, for 30 training breaths per day. Resistance is set to 15% of the participant's maximal inspiratory pressure throughout the eight weeks.	Device: Sham Inspiratory Muscle Strength Training; Daily home-based inspiratory muscle strength training using a POWERbreathe K3 device for eight weeks, at 15% of maximal inspiratory pressure throughout.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Laboratory-Measured Seated Systolic Blood Pressure at 8 Weeks	Seated brachial systolic blood pressure measured in the laboratory with an automated oscillometric monitor after a period of quiet rest. This is the powered primary outcome.	Baseline and 8 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Home Systolic Blood Pressure at 8 Weeks	Self-measured seated brachial systolic blood pressure recorded at home once weekly on a provided automated monitor, following American Heart Association home-monitoring recommendations.	Baseline and 8 weeks

Collaborators and Investigators

• Sponsor: Florida State University
• Collaborators: National Heart, Lung, and Blood Institute (NHLBI)
• Investigators: Principal Investigator: Joseph C Watso, Florida State University

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): September 1, 2028
• Study Completion (Estimated): October 1, 2028

Study Registration Dates

• First Submitted: September 30, 2026
• First Submitted That Met QC Criteria: September 30, 2026
• First Posted (Actual): October 6, 2026

Study Record Updates

• Last Update Posted (Actual): October 8, 2026
• Last Update Submitted That Met QC Criteria: October 7, 2026
• Last Verified: October 1, 2026

More Information

Terms related to this study

• Keywords: hypertension; blood pressure; vascular function; type 1 diabetes; flow-mediated dilation; arterial stiffness; respiratory muscle training; inspiratory muscle strength training
• Additional Relevant MeSH Terms: Endocrine System Diseases; Vascular Diseases; Cardiovascular Diseases; Metabolic Diseases; Autoimmune Diseases; Immune System Diseases; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Hypertension; Diabetes Mellitus, Type 1
• Other Study ID Numbers: STUDY00007503; R03HL183276 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

De-identified individual participant-level data (IPD) that correspond directly to the key outcomes reported in peer-reviewed publications will be preserved and shared.

IPD Sharing Time Frame

Data will be made available after peer-review publication of the final dataset, but no later than 1 year after the completion of data collection. Data will remain available for a period of at least 10 years, per the University's guidelines for records retention.

IPD Sharing Access Criteria

Access will be unrestricted and open to the scientific community without controlled-access barriers. All data will be fully de-identified in compliance with HIPAA guidelines by removing direct/indirect personal identifiers and assigning coded study IDs prior to upload. Datasets will be structured in open, interoperable formats (CSV and/or TXT) requiring no specialized software to access. Datasets will be archived and publicly searchable in Zenodo (a FAIR-aligned public generalist repository) and assigned a persistent Digital Object Identifier (DOI). Summary results will also be submitted directly to ClinicalTrials.gov.

• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No