By Dr. Leandro Pucci, DCN, CNS, CKNS, LDN
A normal hemoglobin A1c doesn't necessarily mean your metabolism is healthy. Insulin resistance can develop years before blood sugar rises. During this time, the pancreas produces extra insulin to keep glucose levels normal, allowing the underlying problem to go unnoticed.
This is why looking beyond standard glucose tests matters. Fasting insulin, HOMA-IR, and the triglyceride-to-HDL ratio can help identify early signs of insulin resistance before blood sugar becomes elevated.
Insulin's job is to move glucose out of the blood and into muscle, liver, and fat cells. In insulin resistance, those cells respond less to the same amount of insulin. The pancreas compensates by releasing more. As long as it can keep up, blood glucose stays in the normal range.
The endocrinologist Gerald Reaven described this compensation in his 1988 Banting Lecture, proposing that insulin resistance and the high insulin levels that accompany it underlie a cluster of problems: elevated triglycerides, low HDL, high blood pressure, and eventually type 2 diabetes. Nearly four decades later, standard screening still focuses on the last step in that sequence.
A1c measures average blood sugar over approximately three months, but it doesn't identify every metabolic problem. Additional testing can provide a more complete picture.
Fasting insulin: Measures how much insulin your body produces to maintain normal blood sugar. Higher levels may indicate insulin resistance.
HOMA-IR: Uses fasting insulin and glucose to estimate insulin resistance. Values above approximately 2–2.5 may indicate a concern, although cutoffs vary (4).
Triglyceride-to-HDL ratio: A higher ratio can signal metabolic dysfunction. A ratio of 3.0 or higher has been associated with insulin resistance in research (5).
Fasting triglycerides: Elevated levels can indicate problems with how the body processes fat.
Waist circumference and liver enzymes: Can provide clues about excess abdominal fat and fatty liver.
Hemoglobin A1c: Measures average blood sugar but may remain normal during early insulin resistance.
Insulin resistance affects more than blood sugar. It is associated with cardiovascular disease, fatty liver, PCOS, and hormonal changes.
A review of 65 studies involving more than 500,000 adults found that those with the highest HOMA-IR levels had a 64% greater risk of coronary heart disease than those with the lowest levels.
Identifying insulin resistance early may help reduce long-term metabolic and cardiovascular risks.
Several factors can contribute to insulin resistance:
Excess abdominal fat: Visceral and liver fat can interfere with insulin signaling.
Low muscle mass and inactivity: Muscle plays a major role in removing glucose from the bloodstream.
Diet: Frequent consumption of refined carbohydrates and sugary drinks can contribute to metabolic dysfunction.
Poor sleep and chronic stress: Both can negatively affect insulin sensitivity.
Medications and hormonal changes: Certain medications and changes in thyroid or sex hormones can play a role.
The good news is that insulin resistance can often improve with consistent lifestyle changes.
1. Improve your nutrition. Reduce refined carbohydrates and added sugars while focusing on whole foods and a sustainable eating pattern. Research shows that lower-carbohydrate diets can improve insulin sensitivity and blood sugar control.
2. Build muscle and stay active. Resistance training two to three times per week helps your body use glucose more efficiently. Walking for 10 minutes after meals can also help reduce blood sugar spikes.
3. Prioritize sleep and manage stress. Poor sleep can quickly affect insulin sensitivity. One study found that a week of restricted sleep reduced insulin sensitivity by approximately 20% in healthy young men.
4. Monitor your progress. Rechecking fasting insulin, HOMA-IR, and triglycerides after approximately 12 weeks can help determine whether your lifestyle changes are making a difference.
Can you have insulin resistance with a normal A1c?
Yes. Insulin resistance can develop years before blood sugar rises because the pancreas compensates by producing more insulin.
What is a healthy fasting insulin level?
Many metabolically healthy adults have fasting insulin below 10 µIU/mL, although laboratory ranges vary. It should be evaluated alongside fasting glucose.
Can thin people have insulin resistance?
Yes. People with a normal BMI can still have insulin resistance, particularly if they have excess visceral fat, low muscle mass, or a family history of diabetes.
How quickly can insulin resistance improve?
Fasting insulin and triglycerides may improve within 4–12 weeks of consistent changes to nutrition, exercise, and sleep.
Is a low-carb diet necessary?
Not always. Reducing refined carbohydrates and added sugars can help, but the best approach depends on individual metabolic health and lifestyle.
Normal blood sugar doesn't always mean your metabolism is healthy. Insulin resistance can develop quietly for years before traditional lab tests identify a problem.
Adding fasting insulin and HOMA-IR to your metabolic testing can provide valuable insight and help guide a more personalized approach to improving your health.
Want to know where you stand? Book a discovery call to review your labs and discuss a personalized plan.
This article is for educational purposes only and is not medical advice.
