Inspiratory Muscle Strength Training in Adults With Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is at epidemic proportions in the United States and worldwide. It is a chronic obesity-associated metabolic disorder characterized by glucose dysregulation combined with insulin resistance and beta-cell defects. First-line T2DM treatments include lifestyle remedies, such as dietary modifications and exercise. Exercise, whether aerobic and/or resistance training, increases whole-body insulin sensitivity and stimulates muscle glucose uptake independent of insulin. The acute effects of exercise on muscle in patients with abnormal glucose regulation produce immediate improvements in blood glucose levels. In addition, when exercise is repeated over time, adaptations occur that include more long-lasting increases in insulin sensitivity. The effects of traditional exercise on glycemic control and insulin sensitivity in patients with T2DM are well established. However, adherence to traditional exercise programs is low, in part, due to lack of time and physical discomfort, and new regimens for T2DM treatment are needed.

Recently, a novel time-efficient respiratory exercise called Inspiratory Muscle Strength Training (IMST) was developed. IMST is distinct from other traditional forms of exercise as it is only 5 minutes per session and performed on a hand-held device during stationary sitting or standing. Typically, IMST comprises 5 sets of 6 inspiratory maneuvers with 1-minute rests between sets. Previous studies demonstrate that 6 weeks of IMST improve systolic blood pressure (SBP), sympathetic nervous system activity, and endothelial function in healthy individuals, middle-aged and older people, and adults with obstructive sleep apnea. These BP-lowering effects of IMST are significant for reducing the risks of cardiovascular disease (CVD), the number one cause of death in people living with diabetes. IMST is safe and tolerable, with adherence rates >90% in diverse populations, and presents a manageable program for improving metabolic health in T2DM patients who have difficulty maintaining a traditional exercise program requiring a large amount of time and physical exertion. It is unknown if IMST, a highly-abbreviated respiratory exercise that is not physically demanding, has beneficial effects on glycemic control and insulin sensitivity, in combination with its improvements on BP measures, in patients with T2DM. The potential for IMST to exert metabolic benefits in diabetic patients warrants assessment

Inclusion criteria

• diagnosed with type 2 diabetes by physician
• fasting plasma glucose levels ≥126 mg/dl and ≤240 mg/dl
• systolic blood pressure between 120-169 mmHg
• stable dose of medication (three months on the same dose)
• weight stable in the prior 3 months (<3.0 kg weight change) and willing to remain weight stable throughout the study
• absence of unstable clinical disease as determined by medical history

Exclusion criteria

• current smoker (including tobacco products, vaping devices, THC, etc…)
• have an uncontrolled medical condition (e.g., cancer)
• myocardial infarction or stroke within the previous 12 months
• performs regular aerobic exercise (>4 bouts/week)
• BMI ≥ 40 kg/m2
• systolic blood pressure <120 or ≥170 mmHg
• diastolic blood pressure >100 or <60 mmHg
• Cheyne-Stokes respiration
• history of perforated eardrum
• history of glaucoma or retinopathy
• history of collapsed lung
• diagnosed with asthma
• pregnant, breastfeeding, or trying to become pregnant (self-reported)
• medications that, in the opinion of the study physician or nurse practitioner, may impact the outcomes of the study (e.g., steroids)