Insulin Resistance — The Silent Precursor to Diabetes

Insulin resistance is a condition where the body's cells become less responsive to insulin, a hormone that helps regulate blood sugar levels. When muscle, fat, and liver cells don't respond well to insulin as they should, the pancreas compensates by producing more insulin to maintain normal blood glucose levels. In 2021, about 97.6 million people in the United States ages 18 and older had prediabetes, which is often associated with insulin resistance.

Insulin resistance doesn't have any symptoms until it turns into prediabetes or Type 2 diabetes, as the pancreas initially produces enough insulin to overcome the resistance. Insulin resistance is thought to precede the development of Type 2 diabetes by 10 to 15 years, making early detection and intervention crucial. While this condition may sound concerning, it's often manageable through lifestyle changes and, when necessary, medical treatment.

Excess body fat, particularly belly fat and fat around organs (visceral fat), is believed to be a primary cause of insulin resistance. Physical inactivity can also lead to insulin resistance, as movement and exercise make the body more sensitive to insulin. Age is another factor, with older people being more prone to insulin resistance, and being sedentary, overweight, or obese increases the risk.

Other factors that may contribute to insulin resistance include genetic predisposition, as scientists have identified several genes that make a person more or less likely to develop insulin resistance. Certain medical conditions such as polycystic ovary syndrome (PCOS), Cushing's syndrome, acromegaly, sleep apnea, and some medications including glucocorticoids and certain antipsychotics can also increase risk. Additionally, insufficient sleep has been shown to cause insulin resistance and increase the risk of developing metabolic diseases.

Healthcare providers may recommend testing for insulin resistance if someone has risk factors such as being overweight, having a family history of diabetes, or showing signs like darkened skin patches. While doctors don't usually test for insulin resistance directly, as the most accurate test is complicated and used mostly for research, they often use related tests to assess metabolic health and diabetes risk.

Testing may be particularly valuable for individuals over age 35, those with a waist measurement of 40 inches or more for men and 35 inches or more for women, or people with other components of metabolic syndrome such as high blood pressure or abnormal cholesterol levels. Early testing can help identify problems before they progress to prediabetes or type 2 diabetes, allowing for timely intervention through lifestyle changes or medical treatment.

For most non-pregnant adults, a fasting glucose level of less than 100 mg/dL is considered normal, while levels of 100-125 mg/dL can indicate prediabetes and insulin resistance. An A1C under 5.7% is considered normal, between 5.7% and 6.4% may indicate prediabetes, and 6.5% or above suggests diabetes. Elevated fasting insulin levels, particularly when combined with normal or slightly elevated glucose levels, may suggest insulin resistance.

It's important to understand that numbers won't always match perfectly - someone can have 'good' fasting glucose levels but a high A1C, or high glucose spikes but 'ok' A1C levels. Healthcare providers typically evaluate these results together along with other factors like family history, weight, and physical symptoms. Abnormal results don't necessarily mean diabetes is inevitable - they often indicate an opportunity to make changes that can help prevent or delay progression to more serious conditions.

The encouraging news is that insulin resistance can often be improved or even reversed through lifestyle modifications. Getting active is probably the best way to combat insulin resistance, as exercise can dramatically reduce insulin resistance in both the short and long terms. Physical activity makes people more sensitive to insulin, which is one reason it's important for diabetes management and good health in general.

Weight management also plays a crucial role, as weight loss for those who have overweight or obesity is another great way to relieve strain on the body and increase insulin sensitivity. Eating a balanced diet with non-starchy vegetables, fruits, whole grains and lean proteins helps reduce blood sugar, which decreases the amount of insulin the pancreas needs to release. Other lifestyle changes like managing stress and getting enough sleep can also help reach health goals.