Understanding Insulin Resistance
While insulin resistance is a hallmark of prediabetes and type 2 diabetes, it can also affect those with type 1.
What is insulin resistance?
People with insulin resistance, also known as impaired insulin sensitivity, have built up a tolerance to insulin, making the hormone less effective. As a result, more insulin is needed to persuade fat and muscle cells to take up glucose and the liver to continue to store it.
Just why a person fails to respond properly to insulin is still a mystery. But there are ways to make the body more receptive to insulin, which can help prevent or delay type 2 diabetes—or help someone with type 1 diabetes manage their blood glucose (blood sugar).
In response to the body's insulin resistance, the pancreas deploys greater amounts of the hormone to keep cells energized and blood glucose levels under control. This is why people with type 2 diabetes tend to have elevated levels of circulating insulin. The ability of the pancreas to increase insulin production means that insulin resistance alone won't have any symptoms at first. Over time, though, insulin resistance tends to get worse, and the pancreatic beta cells that make insulin can wear out. Eventually, the pancreas no longer produces enough insulin to overcome the cells' resistance. The result is higher blood glucose levels, and ultimately prediabetes or type 2 diabetes.
Insulin has other roles in the body besides regulating blood glucose levels, and the effects of insulin resistance are thought to go beyond diabetes. For example, some research has shown that insulin resistance, independent of diabetes, is associated with heart disease.
What causes insulin resistance?
Scientists are beginning to get a better understanding of how insulin resistance develops. For starters, several genes have been identified that make a person more or less likely to develop the condition. It's also known that older people are more prone to insulin resistance. Lifestyle can play a role, too. Being sedentary, overweight or obese increases the risk for insulin resistance. Why? It's not clear, but some researchers theorize that extra fat tissue may cause inflammation, physiological stress or other changes in the cells that contribute to insulin resistance. There may even be some undiscovered factor produced by fat tissue, perhaps a hormone, that signals the body to become insulin resistant.
Doctors don't usually test for insulin resistance as a part of standard diabetes care. In clinical research, however, scientists may look specifically at measures of insulin resistance, often to study potential treatments for insulin resistance or type 2 diabetes. They typically administer a large amount of insulin to a subject while at the same time delivering glucose to the blood to keep levels from dipping too low. The less glucose needed to maintain normal blood glucose levels, the greater the insulin resistance.
What does it mean for your health?
Insulin resistance comes in degrees. The more insulin resistant a person with type 2 is, the harder it will be to manage their diabetes because more medication is needed to get enough insulin in the body to achieve target blood glucose levels.
Insulin resistance isn't a cause of type 1 diabetes, but people with type 1 who are insulin resistant will need higher insulin doses to keep their blood glucose under control than those who are more sensitive to insulin. As with type 2, people with type 1 may be genetically predisposed to become insulin resistant, or they may develop resistance due to being overweight. Some research indicates that insulin resistance is a factor in cardiovascular disease and other complications in people with type 1.
What can you do about it?
While it may not be possible to defeat insulin resistance entirely, there are ways to make the body’s cells more receptive to insulin.
- Getting active is probably the best way to combat insulin resistance. Exercise can dramatically reduce insulin resistance in both the short and long terms. In addition to making the body more sensitive to insulin and building muscle that can absorb blood glucose, physical activity opens up an alternate gateway for glucose to enter muscle cells without insulin acting as an intermediary, reducing the cells' dependence on insulin for energy. While this doesn't reduce insulin resistance itself, it can help people who are insulin resistant improve their blood glucose control.
- Weight loss can also cut down on insulin resistance. No single diet has been proved to be the most effective. Some evidence suggests, though, that eating foods that are low in fat and high in carbohydrates can worsen insulin resistance. Research has also shown that people who undergo weight-loss surgery are likely to become significantly more sensitive to insulin.
- No medications are specifically approved to treat insulin resistance. Yet diabetes medications like metformin and thiazolidinediones, or TZDs, are insulin sensitizers that lower blood glucose, at least in part, by reducing insulin resistance.
Don’t give up
While fighting an invisible foe can feel frustrating and discouraging, know that you are not alone. There are effective tactics to combat insulin resistance. Losing weight, exercising more or taking an insulin-sensitizing medication can help you get back to good blood glucose control and better health.