What is insulin?
Insulin is a hormone made in the pancreas. Insulin plays a major role in metabolism—the way the body uses digested food for energy. The digestive tract breaks down carbohydrates into glucose. Glucose is a form of sugar that enters the bloodstream. With the help of insulin, cells throughout the body absorb glucose and use it for energy.
Insulin’s Role in Blood Glucose Control
When blood glucose levels rise after a meal, the pancreas releases insulin into the blood. Insulin and glucose then travel in the blood to cells throughout the body.
- Insulin helps muscle, fat, and liver cells absorb glucose from the bloodstream, lowering blood glucose levels.
- Insulin stimulates the liver and muscle tissue to store excess glucose. The stored form of glucose is called glycogen.
- Insulin also lowers blood glucose levels by reducing glucose production in the liver.
In a healthy person, these functions allow blood glucose and insulin levels to remain in the normal range.
What is insulin resistance?
In insulin resistance, muscle, fat, and liver cells do not respond properly to insulin and thus cannot easily absorb glucose from the bloodstream. As a result, the body needs higher levels of insulin to help glucose enter cells.
The pancreas tries to keep up with this increased demand for insulin by producing more. As long as it is able to produce enough insulin to overcome the insulin resistance, blood glucose levels stay in the healthy range. Over time, insulin resistance can lead to type 2 diabetes and prediabetes because the pancreas fails to keep up with the body’s increased need for insulin. Without enough insulin, excess glucose builds up in the bloodstream, leading to diabetes, prediabetes, and other serious health disorders.
What causes insulin resistance?
Although the exact causes of insulin resistance are not completely understood, scientists think the major contributors to insulin resistance are excess weight and physical inactivity. (See “Two Simple Things You Can Do Now To Start Reversing Diabetes.“)
Some experts believe obesity, especially excess fat around the waist, is a primary cause of insulin resistance. Studies have shown that belly fat produces hormones and other substances that can cause serious health problems such as insulin resistance, high blood pressure, imbalanced cholesterol, and cardiovascular disease.
Belly fat plays a part in developing chronic, or long-lasting, inflammation in the body. Chronic inflammation can damage the body over time, without any signs or symptoms. This can contribute to the development of insulin resistance, type 2 diabetes, and heart disease. Studies show that losing weight can reduce insulin resistance and prevent or delay type 2 diabetes. (See “Is It Possible To Reverse Diabetes?“)
Many studies have shown that physical inactivity is associated with insulin resistance, often leading to type 2 diabetes. In the body, more glucose is used by muscle than other tissues. Normally, active muscles burn their stored glucose for energy and refill their reserves with glucose taken from the bloodstream, keeping blood glucose levels in balance.
Studies show that after exercising, muscles become more sensitive to insulin, reversing insulin resistance and lowering blood glucose levels. Exercise also helps muscles absorb more glucose without the need for insulin. The more muscle a body has, the more glucose it can burn to control blood glucose levels.
Other causes of insulin resistance may include ethnicity, diseases, hormones, steroid use, medications, age, sleep problems, and cigarette smoking.
Does sleep matter?
Yes. Studies show that untreated sleep problems, especially sleep apnea, can increase the risk of obesity, insulin resistance, and type 2 diabetes. Night shift workers may also be at increased risk for these problems. (See “Are You Sleep Deprived” interview with Dr. Raj Dasgupta.)
What is Prediabetes?
Prediabetes is a condition in which blood glucose or A1C levels are higher than normal but not high enough for a diagnosis of diabetes. Prediabetes is becoming more common in the United States. People with prediabetes are at increased risk of developing type 2 diabetes.
How does insulin resistance relate to type 2 diabetes and prediabetes?
Prediabetes usually occurs in people who already have insulin resistance. Although insulin resistance alone does not cause type 2 diabetes, it often sets the stage for the disease by placing a high demand on the pancreas. In prediabetes, the pancreas can no longer produce enough insulin to overcome insulin resistance, causing blood glucose levels to rise above the normal range.
Once a person has prediabetes, continued loss of pancreas cell function usually leads to type 2 diabetes. People with type 2 diabetes have high blood glucose. Over time, high blood glucose damages nerves and blood vessels, leading to complications such as heart disease, stroke, blindness, kidney failure, and lower-limb amputations.
Studies have shown that most people with prediabetes develop type 2 diabetes within 10 years, unless they change their lifestyle. Lifestyle changes include losing 5 to 7 percent of their body weight by making changes in their diet and level of physical activity.
What are the symptoms of insulin resistance and prediabetes?
Insulin resistance and prediabetes usually have no symptoms. People may have one or both conditions for several years without knowing they have them. Even without symptoms, health care providers can identify people at high risk by their physical characteristics, also known as risk factors.
If you’re at risk for developing prediabetes or if you’ve already been diagnosed with prediabetes, schedule a phone call with me to discuss how we can work together to reverse it before it’s too late. In just a few weeks I will be opening up spots in my program Beating Diabetes: The 10 Week Roadmap, but there are limited spots. More details coming soon!