What insulin resistance is, and why A1c can still look normal
Insulin resistance is a state in which your cells stop responding well to insulin, so the pancreas has to make more of it to move sugar out of the blood. The NIDDK describes it as muscle, fat and liver cells not responding well to insulin, which can lead to higher blood sugar and weight gain over time.
The key point is timing. As long as the pancreas can keep up, blood sugar stays normal. MedlinePlus explains that extra insulin can keep glucose in a healthy range for a while, but over time the pancreas may not be able to make enough. During those compensated years, standard sugar tests look fine:
| Stage | Fasting insulin | Fasting glucose | HbA1c |
|---|---|---|---|
| Healthy | Normal | Under 100 mg/dL | Under 5.7% |
| Compensated insulin resistance | High | Usually under 100 mg/dL | Usually under 5.7% |
| Prediabetes | Often high | 100 to 125 mg/dL | 5.7 to 6.4% |
| Type 2 diabetes | High, then may fall | 126 mg/dL or higher | 6.5% or higher |
The glucose and A1c cutoffs come from the NIDDK and the MedlinePlus A1c guide, which notes that A1c reflects average blood sugar over about three months. Because A1c tracks glucose rather than insulin, it stays reassuring until compensation starts to fail.
Signs that suggest it
Insulin resistance has no symptoms of its own, but it leaves fingerprints. Common ones in men include:
- A growing waist, especially fat that feels firm around the middle.
- High triglycerides and low HDL cholesterol on a routine lipid panel.
- Mildly raised liver enzymes from fatty liver.
- Dark, thick, velvety skin on the neck or armpits (acanthosis nigricans), which MedlinePlus lists as a risk marker.
- Blood pressure creeping up.
- Low testosterone, low energy and difficulty losing weight.
The NIDDK lists overweight, obesity and a large waist among the main risk factors, along with older age, family history and inactivity.
Measuring insulin directly: fasting insulin and HOMA-IR
Measuring fasting insulin gives a direct look at how hard the pancreas is working. Paired with fasting glucose from the same draw, it can be turned into HOMA-IR, a score from the homeostasis model assessment developed in 1985. In US units it is fasting insulin (in microunits per mL) multiplied by fasting glucose (in mg/dL), divided by 405. Higher scores mean more resistance.
It is important to be honest about the limits:
- No universal cutoff. Thresholds used in studies vary by population and lab, so a HOMA-IR value is read as a trend and in context, not as a pass or fail.
- Lab methods differ. MedlinePlus notes that insulin reference ranges vary between laboratories.
- It is not how diabetes is diagnosed. The NIDDK says health care professionals may not test for insulin resistance, and that the formal test is mainly used in research. Diagnosis of prediabetes and diabetes still rests on glucose and A1c.
Within those limits, a high fasting insulin in a man with a normal A1c is useful information: it flags risk years earlier and gives a number that should fall as treatment works. Our pages on the fasting insulin test and the HOMA-IR score explain preparation and interpretation.
Getting an accurate result
Preparation makes a big difference to an insulin number. MedlinePlus advises fasting, with no food or drink other than water, for 8 to 12 hours, and stopping biotin supplements for at least a day beforehand because biotin can interfere with the test. A morning draw after a normal night’s sleep is the most consistent. A very hard workout, a heavy late dinner or an illness in the days before can all nudge the result, so repeat testing under the same conditions is the fair way to judge a trend. Men who use insulin for diabetes need a different approach, since injected insulin affects the measurement.
Why men with belly fat and low testosterone are worth testing
Belly fat, insulin resistance and low testosterone feed each other, so finding one is a reason to look for the others. In a study of 580 men with type 2 diabetes, 43 percent had low total testosterone, and low testosterone was independently linked to insulin resistance; as insulin resistance changed over time, testosterone moved in the opposite direction.
The connection runs through visceral fat and SHBG. Insulin resistance lowers SHBG, and fat tissue lowers testosterone production signals, which is covered in our page on obesity and low testosterone. For a man who already has a large waist and a low testosterone result, a normal A1c is not the end of the metabolic story, and fasting insulin is a reasonable next measurement.
Treatment paths
The good news is that insulin resistance responds to changes you can measure. The core levers are:
- Weight loss, particularly visceral fat. Even modest loss improves insulin sensitivity.
- Strength training, because muscle is the main place glucose is stored.
- Aerobic activity and daily walking, especially after meals.
- Sleep, since short sleep worsens insulin sensitivity.
- Fewer refined carbohydrates and sugary drinks, and more protein and fiber.
When weight is part of the problem and criteria are met, Ultimate Male’s medical weight loss program uses semaglutide or tirzepatide with labs and body composition tracking. Testosterone therapy is considered only when low testosterone is confirmed on repeat morning tests with symptoms; it is not a treatment for insulin resistance on its own. If diabetes medication is needed, the clinic coordinates with your primary care doctor. For men already in the prediabetes range, the page for men with prediabetes covers the next steps.
When high blood sugar is urgent
Insulin resistance is not an emergency, but very high blood sugar can be. Seek same-day care for extreme thirst, frequent urination, blurred vision and unexplained weight loss. Go to the emergency room or call 911 for confusion, heavy, rapid breathing, a fruity smell on the breath, or vomiting that will not stop.
Your next step
If your waist is growing, your testosterone is low or your triglycerides are high, a fasting panel that includes insulin can show what A1c alone misses. Ultimate Male draws fasting labs on site at San Gabriel and Downey with results in 24 to 48 hours, and a PA-C or MD reviews them with you. Start with the free 10-minute phone call at 626-319-5261 or book a morning appointment.
