Insulin resistance (IR) is a condition where more insulin is produced by the body in response to diet, resulting in the body's cells becoming less responsive to insulin. Insulin's job is to push glucose into cells, including fat cells, muscle cells, the brain, and other tissues. Over time, insulin's ability to control blood glucose levels diminishes, and this may lead to prediabetes and type 2 diabetes. Insulin resistance is often silent in its early stages. However, several signs and symptoms may indicate the presence of IR. Understanding these early warning signs is crucial for taking proactive steps to reverse IR.

What Is Insulin Resistance?
Before diving into the signs, it's important to understand how IR works. When we eat, food is broken down into glucose (sugar), which enters the bloodstream. Insulin, a hormone produced by the pancreas, helps the cells of the body take up glucose from the blood and use it for energy. In someone with IR, the body's cells do not respond effectively to insulin due to changes to the insulin receptors, meaning more insulin is required to help glucose enter the cells. This leads to higher levels of insulin in the blood (hyperinsulinemia) and can cause the pancreas to overproduce insulin over time, further exacerbating the problem.
From a normal insulin state to type 2 diabetes mellitus or type 2 diabetes (T2DM) takes about 10-12 years. IR is present in all of the stages beyond a normal state. First, a person will have elevated insulin levels that are unfortunately or often not found. Think of IR as pre-pre-diabetes. A person will have normal fasting glucose levels, A1c levels (also called hemoglobin A1c), and postprandial glucose levels (levels after eating). Most health insurance companies cover annual screening for prediabetes/diabetes with a fasting glucose level with or without an A1c. After a period of years, IR will likely progress to pre-diabetes. This will be found when the glucose-related labs (underlined above) start to be abnormally high. If any one of these tests is abnormal and in the prediabetes range, prediabetes exists. Once prediabetes is present, 1/3 of people with prediabetes will progress to full-blown T2DM, 1/3 will continue to be prediabetic, and 1/3 will reverse the disease. All stages are reversible with lifestyle; however, the longer a person has T2DM, the higher the chance the condition cannot be fully reversed, even with aggressive lifestyle changes.
Key Signs and Symptoms of Insulin Resistance
Skin Tags and Darkened Skin
I’m often surprised when I meet new patients who have skin changes consistent with IR but are completely unaware of it. For example, many don’t realize that their neck has a dark, “dirty” appearance that doesn’t go away, even with regular washing. One of the most common signs of insulin resistance is a skin condition called acanthosis nigricans (AN). This chronic skin change typically affects areas like the back of the elbows, fronts of the knees, outside of the ankles, the neck, the groin, and the armpits. The skin in these areas may have a dark, almost dirty appearance that resists cleaning. In addition, the skin can develop dark, velvety patches or dark skin tags. These skin changes are important warning signs and can help identify IR long before more serious health issues develop.
Abdominal Obesity - Belly Fat Weight Gain, Particularly Around the Abdomen
Having an increased waist circumference is a significant health concern and risk for IR. For women in the United States, a waist circumference of 35 inches or greater is considered a risk factor, while for men, the threshold is 40 inches or greater. However, for women of Hispanic or Asian descent, the recommended waist circumference should not be greater than 31 inches, and for men, it should not exceed 35 inches. Excess abdominal fat, as indicated by waist circumference, is closely linked to an increased risk of conditions such as IR, heart disease, and type 2 diabetes.
Your Diet, Food Cravings
What you eat—and the foods you're drawn to—can be signs that you may have IR. A diet that is very heavy in carbohydrates can contribute to the development of IR. While a plant-based diet is often considered healthy, it is high in carbohydrates. I see patients who are long-term vegans or vegetarians who have IR. If you find yourself binge eating carbohydrates or constantly feeling hungry—even shortly after eating—these could be potential signs of IR.
Your BMI
Although I agree that BMI doesn't tell the whole story, it can still serve as a helpful guide. Elevated BMI should be viewed as a potential sign of IR, do not think that having a "normal" BMI means that there is no chance of IR. Having a normal BMI and being "skinny fat" is a risk for IR.
Odds of IR increase with BMI. For some individuals, laboratory testing of fasting insulin levels can provide additional insight. As BMI increases, the "normal" range for insulin levels can shift upward on the laboratory interpretation guide. In this context, escalating ranges may be considered "normal" or expected for a BMI range, but in actuality, it is abnormal as fasting insulin should be low.
Elevated Triglycerides (TG) and/or Low HDL
When your cholesterol is checked, and you are told that it's fine, often the doctor is telling you that the total cholesterol and LDL cholesterol are in the normal range. This may not tell the whole picture. Elevated triglycerides and/or low HDL cholesterol are laboratory findings consistent with IR.
Any Metabolic Condition or Risk Factor. Elevated Blood Pressure
There are five findings or conditions that are part of metabolic syndrome. Having any one of them may mean that you have IR, or that you are at risk for it. The five conditions/findings are increased waist circumference, elevated blood pressure, high triglycerides, low HDL, and pre-diabetes/diabetes/IR. Currently, only 6.8% of the adult population in the US has none of these conditions.
Irregular, Infrequent Periods
Menstrual irregularity may be a sign that you have polycystic ovarian syndrome or PCOS. PCOS is more likely if a woman has hirsutism or abnormally heavy body or facial hair growth. Unfortunately, the majority of women with PCOS have IR, with studies finding 64 to 85% with a higher risk in women who are overweight or obese. Even lean women with PCOS, 20 to 25%, will have IR.
Frequent Urination and Increased Thirst
If present, these symptoms may be a clear sign of diabetes. If diabetes is present, a person who has had IR for 10-12 years is now past the first and second stages of IR, pre-pre-diabetes and pre-diabetes.
Brain Fog and Difficulty Concentrating
Many conditions and situations may cause brain fog, and IR is one of them. If this symptom occurs, it is time to see your doctor.
Fatigue
IR can cause persistent fatigue. As with brain fog, many things can cause fatigue, and you should see your doctor for further evaluation.
What to Do if You Suspect Insulin Resistance
First, don't brush off any of the signs or assume they are or are not signs of IR. Seek medical evaluation with bloodwork. Even if all signs point to IR, get checked by your doctor and start the work to reverse the presence of a high insulin state. Get regular labs to measure your progress.
If you do not have any of the signs or symptoms, get an annual evaluation with bloodwork to evaluate for this sneaky condition. Keep track of not only your weight but your waist circumference. Remember, the conditions of IR are reversible with early lifestyle intervention.
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