Business of Wellness
Insulin Resistance - Hiding in Plain Sight by Morgan Nolte, PT, DPT and Beth Smith, PT, DPT As geriatric physical therapists, we couldn’t help noticing that the people we were treating rarely had just diabetes, heart disease, or dementia. In varying degrees of severity, these conditions usually occured together. They were accompanied by both increased fat mass, and decreased muscle mass. Something was off. Chart after chart review revealed elevated cholesterol, high blood pressure, and high blood glucose. For each of these, a separate medication was prescribed, creating polypharmacy. While the world continues to adjust to the constantly changing COVID-19 pandemic, there is another condition that has been steadily growing, largely undetected for the last several decades. A 2019 study analyzed metabolic health data such as fasting blood glucose, hemoglobin A1c, blood pressure, HDL, triglycerides, and waist circumference from 2006 - 2019 and found that approximately 88% of American adults have this condition.1 What could be so prevalent, yet undiagnosed? The answer is insulin resistance. Insulin resistance is an impaired biologic response to insulin stimulation of target tissues, primarily the liver, muscle, and adipose tissue (peripheral insulin resistance) and the brain (central insulin resistance). Insulin resistance impairs glucose disposal, resulting in a compensatory increase in beta-cell insulin production and subsequent hyperinsulinemia. The metabolic consequences of insulin resistance can result in hyperglycemia, hypertension, dyslipidemia, visceral adiposity, hyperuricemia, elevated inflammatory markers, endothelial dysfunction, and a prothrombotic state.2 What is causing this metabolic disease? Insulin resistance experts like Dr. Jason Fung, author of The Obesity Code, and Dr. Benjamin Bikman, author of Why We Get Sick, shed light on the fact that insulin resistance lies at the heart of many of the diseases we treat in geriatric physical therapy. A 2018 study found that trajectories of fasting blood glucose, body mass index (BMI), and insulin sensitivity could detect the start of type 2 diabetes 2 decades prior to its diagnosis.3 Think of it: physical therapists attuned to wellness have the opportunity to educate and guide reversal of early risk factors caused by insulin resistance at least 20 years before disease is diagnosed. We’ve all heard the saying, “When the tide comes in, all the boats rise.” In this case, the tide is insulin. When insulin goes down to healthy levels, all other health markers fall into
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place. Glucose, triglycerides, blood pressure, visceral belly fat, and small, dense LDL go down. HDL and large buoyant LDL go up.2 When one condition is prevented by lowering insulin resistance, we prevent many. When we prevent illness, we prevent future polypharmacy, hospitalizations, and falls. We lower the financial, physical, social, emotional, and mental toll that robs an ageing adult’s quality of life. We help add years to their life and life to their years. Factors that contribute to insulin resistance In The 7 Habits of Highly Effective People, Stephen Covey’s second habit is to begin with the end in mind. With reversing insulin resistance being the end, it is wise to consider what causes insulin resistance. Below are several, but certainly not all, contributing factors. Visceral belly fat Adipose tissue is now recognized as an endocrine organ.4 Far from simply being a place where extra energy is stored, adipose tissue is metabolically active and plays an important role in our reproductive and immune systems.5 Visceral belly fat releases several inflammatory substances. Low-grade chronic systemic inflammation, common in people with central obesity, is associated with the development of atherosclerosis, type 2 diabetes, and hypertension, well known comorbidities that adversely affect the outcomes of persons with COVID-19. The same chronic low-grade inflammation that contributes to more severe COVID-19 cases is what contributes to more insulin resistance.6 Ageing and menopause Ageing increases insulin resistance due to a decline in lean muscle mass, which serves as a valuable reserve for glucose deposit, and increased insulin receptors. The more muscle mass one has, the more insulin sensitivity they enjoy. Women who are experiencing hormonal changes of menopause experience a rise in insulin resistance as estrogen falls.7 Estrogen is protective against insulin resistance and visceral belly fat. Therefore, a shift in fat mass distribution towards the belly is common in middle-aged women and accelerates after menopause, as does her risk for type 2 diabetes and heart disease. Chronic stress There are 2 ways in which glucose may enter a cell through the GLUT4 transporter, muscle demand, and insulin. Our natural stress response is designed to help us utilize the former in preparation to fight or flee a stressor.
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