- Symptoms early on
- Usually none
- Prediabetes A1C range
- 5.7% to 6.4%
- Prediabetes fasting glucose
- 100 to 125 mg/dL
- Weight loss linked to lower risk (DPP)
- 5% to 7% of body weight
What is happening inside the body
After a meal, insulin acts like a key that lets glucose move from your blood into cells. With insulin resistance, the lock is stiff. The pancreas responds by producing extra insulin, which keeps glucose in range for a while.
Over time the pancreas may not keep up. That is when fasting glucose and A1C begin to climb into the prediabetes range, and eventually into type 2 diabetes. The CDC estimates that more than 2 in 5 American adults have prediabetes, and many do not know it.
Common risk factors
- Excess weight, especially around the waist.
- Physical inactivity and loss of muscle mass.
- Age (NIDDK lists 35 and older; CDC lists 45 and older for prediabetes).
- Family history of type 2 diabetes, or a history of gestational diabetes.
- Polycystic ovary syndrome, sleep apnea and some medicines such as glucocorticoids.
- Smoking.
How it is assessed
There is no single routine test for insulin resistance. NIDDK notes that direct insulin resistance testing is used mainly in research. In clinic, doctors diagnose prediabetes with an A1C, fasting plasma glucose or oral glucose tolerance test.
Some clinicians also look at fasting insulin or a calculated score such as HOMA-IR, plus waist size, triglycerides and HDL cholesterol. These can suggest insulin resistance earlier, though cutoffs are not standardized.
What can improve it
In the Diabetes Prevention Program, losing 5% to 7% of starting weight through eating changes and about 150 minutes a week of activity lowered the chance of developing diabetes. Metformin also delayed diabetes in that study. Strength training helps because muscle is a major site of glucose uptake, and good sleep matters too.
For some adults with obesity or prediabetes, a clinician may discuss GLP-1-based medicines or metformin as part of a broader plan. At HealifyMD, a licensed clinician reviews your labs and history before recommending anything.
Why it matters in midlife
Midlife brings several forces that push in the same direction: gradual muscle loss, less daily movement, more abdominal fat, lighter or more broken sleep and, for women, the hormonal shifts of perimenopause. Insulin resistance also travels with other problems, including high triglycerides, fatty liver and high blood pressure, sometimes grouped together as metabolic syndrome. Catching it early gives you more room to change course.
Insulin resistance: common questions
Can you feel insulin resistance?
Most people have no symptoms. Some notice weight gain around the middle or darkened skin patches on the neck, but labs are needed to assess it.
Is insulin resistance the same as prediabetes?
Not exactly. Insulin resistance is the underlying problem; prediabetes is a diagnosis made when blood sugar has already risen above normal.
Can thin people be insulin resistant?
Yes. Genetics, low muscle mass, inactivity, poor sleep and some medicines can cause it at a normal weight.
Does menopause affect insulin sensitivity?
The hormonal shifts of the menopause transition are associated with more abdominal fat and changes in metabolism, which can worsen insulin sensitivity for some women.
Is it reversible?
It can often be improved substantially with lifestyle change and, when appropriate, medication. Progress is tracked with repeat labs.
Which labs should I ask about?
A1C and fasting glucose are the standard tests. Your clinician may add fasting insulin, lipids and liver tests depending on your history.
Sources
We cite government agencies, professional societies and peer-reviewed research. See our editorial policy.
- Insulin Resistance & PrediabetesNational Institute of Diabetes and Digestive and Kidney Diseases
- Prediabetes: Your Chance to Prevent Type 2 DiabetesCenters for Disease Control and Prevention
- Insulin in bloodMedlinePlus (U.S. National Library of Medicine)