Normal blood sugar but insulin resistant? How to find out

Most people see their fasting glucose and A1C come back marked normal and assume everything is fine. This conversation explains why that is not the whole story. You can have normal blood sugar and still be insulin resistant, because blood sugar is the last thing to go up when metabolism breaks down. The first thing to rise is insulin, and almost nobody checks it.

What blood sugar and insulin actually do

Glucose is the main sugar your body uses as fuel. It comes from starchy foods, grains, beans and sugar. When you eat sugar or starch, the pancreas releases insulin, which helps glucose get inside your cells. A small rise after eating is normal. A flat glucose line is not the goal.

The problem starts when you keep eating large amounts of starch and sugar. At its peak, the average American ate about 152 pounds of sugar and 133 pounds of flour a year, which Mark Hyman calls a pharmacologic dose. Your body keeps blood sugar normal by making more and more insulin, and your cells become resistant to it. High insulin locks fat inside fat cells, so you cannot break it down. It also drives hunger and cravings, like starving in the midst of plenty. Diabetes is a very late stage, often decades after the process began.

Why a normal result can hide a problem

The sequence of events matters:

1. Insulin rises after meals while fasting glucose and fasting insulin stay normal.
2. Fasting insulin starts to rise.
3. Glucose rises after meals or on a glucose tolerance test.
4. Fasting glucose and A1C go up last.

One example is a patient who drank the equivalent of two colas for a glucose tolerance test. Her glucose never passed 110, but her insulin hit about 300. Doctors who check only glucose miss many cases. Reference ranges also mislead. The lab's normal fasting insulin goes up to 18, yet the guest argues it should be 5 or less.

Numbers worth knowing

• Fasting glucose: 70 to 90. An Israeli study found cardiovascular risk rising linearly above 87.
• Fasting insulin: ideally under 5. Between 5 and 10 deserves attention.
• Hemoglobin A1C: about 5.0 to 5.2. Quest data showed cardiovascular risk rising once A1C passes 5.1, well below the 5.7 prediabetes cutoff.
• Post meal glucose: ideally under 110, 120 at most. On a two hour glucose tolerance test, it should never exceed 140.
• Insulin resistance score: a test using mass spectrometry to measure insulin and C peptide, on a scale of 0 to 100, available as an add on at Function.

If you could pick one blood test, the answer is insulin, by far.

Clues you can find without a lab

Insulin resistance leaves traces. The simplest is belly fat, which the guest calls the mirror test: if your stomach jiggles when you jump, get checked. A tape measure helps too, since waist to hip ratio should be under 0.8 for men and under 0.9 for women. Other clues include:

• Triglycerides above 100 to 150, low HDL, small lipid particles and high ApoB.
• Fatty liver, shown by high ALT or GGT. A FibroScan or full body MRI can confirm it.
• High uric acid, high CRP, protein in the urine and low testosterone.
• In women, PCOS features such as high testosterone, DHEA and LH to FSH ratio.
• Darkened skin in the armpits or neck, sleep apnea, a family history of diabetes or gestational diabetes, and statin use.

You can also be thin and still insulin resistant. The guest uses the term TOFI, thin on the outside, fat on the inside. A DEXA body composition scan shows it, and people of South Asian and Asian origin can show it at normal body weights.

What moves your glucose after a meal

A continuous glucose monitor reveals how you respond to food. A few weeks of tracking is enough for most people, and it is essential for type one diabetes. Several factors change your curve:

• Meal order and composition. Bread and wine first sends glucose through the roof, while protein, fat and fiber first blunts it.
• Whole foods and fiber. A bean or a piece of fruit behaves differently from juice.
• Portion size. Even healthy food can spike glucose if you overeat.
• Sleep and stress. Poor sleep raises cravings, and cortisol releases stored glucose even without eating.
• Movement. A 10 to 20 minute walk after eating smooths the spike.
• Genetics and microbiome. The same food can affect two people very differently.

How to reverse insulin resistance

The guest says it is possible, and describes a person with type two diabetes who was on insulin for ten years, was off it within three days and saw A1C fall from 11 to 5.5 in three months without drugs. This is one clinician's account, not a trial, so work with your own doctor.

The principles are simple:

1. Cut starch and sugar for the most part.
2. Eat protein, fat and at least 30 grams of fiber a day.
3. Walk 10 to 20 minutes after meals.
4. Build strength, since muscle absorbs glucose even without insulin.
5. Sleep enough and manage stress.
6. Give yourself a 12 to 14 hour overnight fast.

Artificial sweeteners are not a free pass, since they can raise cravings and affect the microbiome. Monk fruit and a little stevia are the exceptions mentioned.

Conclusion

Knowing your blood sugar is not enough. Measure fasting insulin and A1C, check your waist and body composition, and then use food, movement, sleep and stress control to bring the numbers down.