Insulin, a hormone that the pancreas makes, allows cells to absorb and use glucose. In people with insulin resistance, the cells are unable to use insulin effectively.
When the cells cannot absorb glucose, levels of this sugar build up in the blood. If glucose, or blood sugar, levels are higher than usual but not high enough to indicate diabetes, doctors refer to this as prediabetes.
Prediabetes often occurs in people with high insulin resistance. Around 1 in 3 people in the United States have prediabetes, according to figures from the Centers for Disease Control and Prevention (CDC).
In this article, we look at the current understanding of insulin resistance and explain its role as a risk factor for diabetes and other conditions.
We also describe the signs and symptoms of insulin resistance and ways to avoid it.
Insulin resistance occurs when excess glucose in the blood reduces the ability of the cells to absorb and use blood sugar for energy.
If the pancreas can make enough insulin to overcome the low rate of absorption, diabetes is less likely to develop, and blood glucose will stay within a healthy range.
How does insulin resistance become diabetes?
In a person with prediabetes, the pancreas works increasingly hard to release enough insulin to overcome the body's resistance and keep blood sugar levels down.
Over time, the pancreas' ability to release insulin begins to decrease, which leads to the development of type 2 diabetes.
Insulin resistance remains a major feature of type 2 diabetes.
Insulin is essential for regulating the amount of glucose that circulates in the bloodstream. It induces the cells to absorb glucose.
Insulin is also the chemical messenger that instructs the liver to store some glucose, rather than releasing it into the bloodstream. The liver packages glucose for storage in the form of glycogen.
Insulin usually helps the body maintain a good balance of energy, never allowing the level of blood glucose to spike for too long.
The reasons for insulin resistance remain complex, and researchers continue to investigate.
- The following steps outline the medical community's current understanding of insulin resistance:
- The body's cells become less affected by insulin.
- This resistance initially causes the pancreas to secrete more insulin, in order to maintain safe blood sugar levels.
- The pancreas becomes unable to maintain the release of extra insulin to compensate for the cells' increasing resistance.
- Consistently high levels of blood glucose develop, progressing into prediabetes and type 2 diabetes if a person does not adopt management strategies and receive treatment.
Insulin resistance does not usually present symptoms until diabetes develops. The CDC report that 90 percent of people with prediabetes are not aware that they have the condition.
Insulin resistance can also lead to the following health issues:
- Acanthosis nigricans: This skin condition can develop in people with insulin resistance. It involves dark patches forming on the groin, armpits, and the back of the neck.
- Polycystic ovary syndrome (PCOS): Insulin resistance can worsen the symptoms of PCOS, which can include irregular menstrual cycles, infertility, and periods that cause pain.
The following are risk factors for insulin resistance, prediabetes, and diabetes:
- being overweight or having obesity, especially when the extra weight is around the midriff
- a sedentary lifestyle or one that is low in exercise
- sleep issues
- high blood pressure, which one 2018 study has linked to an increased risk of insulin resistance
Certain risk factors for prediabetes and diabetes are also risk factors for heart disease and other cardiovascular and cerebrovascular health concerns, such as stroke and heart disease.
Because some of these risk factors are widespread and may be avoidable, such as obesity, health authorities are increasing their focus on lifestyle measures that can help reduce the risk of the disease.
The U.S. Department of Health and Human Services recommend that all people who are overweight and over 45 years of age receive testing for diabetes.
A number of tests can help diagnose prediabetes and diabetes:
- A1C test: This measures a person's average blood sugar level over the previous 2–3 months.
- Fasting blood glucose test: A doctor checks glucose levels after a person refrains from eating or drinking for 8 or more hours.
- Random glucose test: This involves a medical professional checking blood glucose levels at some point during the day.
Doctors usually request more than one of these tests to ensure an accurate diagnosis.
If blood sugar levels consistently fall outside of a normal range, it might indicate that the body is becoming resistant to insulin.
It is not possible to influence some risk factors for insulin resistance and type 2 diabetes, such as family history and genetic makeup.
However, a person can take some steps to reduce the chances of becoming insulin resistant. Some of the same strategies are key to preventing heart disease and stroke.
Also, the American Heart Association (AHA) report that individuals can reduce the risk of type 2 diabetes by making preventive lifestyle changes, primarily by losing weight and increasing physical activity.
Muscles become more sensitive to insulin after exercise, and a person can reverse insulin resistance with an active, healthful lifestyle.
While a diagnosis of insulin resistance or prediabetes might cause alarm, making rushed lifestyle changes and expecting immediate results is not a sustainable way to proceed.
Instead, increase levels of physical activity gradually, replace one item per meal with a healthful, low-carbohydrate option, and be sure to keep this up, week after week.
The most effective way to reduce insulin resistance is to make slow, sustainable changes.
Prediabetes is only a warning.
Research, including that involving the landmark Diabetes Prevention Program, shows that lifestyle changes can reduce the risk of prediabetes progressing to diabetes by over 58 percent.
Start taking steps today to reduce insulin resistance and the risk of diabetes.
I have type 2 diabetes. Will I need to start taking insulin every day?
No, having type 2 diabetes does not automatically mean that you will need to take insulin. For some people, especially in the early stages, simply changing your diet to limit the carbohydrate intake and increasing the amount of exercise can control blood sugar.
The next step for treatment is usually oral medication. While type 2 diabetics sometimes requires insulin, other treatment plans are generally tried before advancing to insulin.