Summary
Insulin resistance can exist for years before blood sugar levels become abnormal, meaning standard glucose tests may miss early-stage metabolic dysfunction. Dr. Berg explains that testing fasting insulin levels — rather than fasting glucose — provides a more accurate picture of where someone is on the path toward type 2 diabetes. Normal blood sugar with insulin resistance represents an early, pre-pre-diabetes stage that can be identified and addressed.
Key Takeaways
- Normal blood sugar does not rule out insulin resistance — the two can coexist, especially in early stages.
- Standard doctor visits typically test blood glucose, not insulin levels, which can miss the problem entirely.
- Insulin resistance can precede type 2 diabetes by up to 10 years.
- The progression follows a chain: insulin resistance → elevated insulin → eventual blood sugar dysregulation → pre-diabetes → type 2 diabetes.
- When cells resist insulin, the pancreas compensates by producing increasingly more insulin, keeping blood sugar temporarily normal.
- Requesting a fasting insulin test (not just a fasting glucose test) is the key diagnostic step to detect early-stage insulin resistance.
- Elevated fasting insulin levels confirm insulin resistance even when blood glucose appears normal.
Details
The Chain of Events Leading to Diabetes
Dr. Berg outlines a clear progression that begins long before blood sugar readings become problematic:
- Insulin resistance develops — cells stop responding effectively to insulin.
- Insulin fails to enter cells normally, triggering a feedback signal to the pancreas.
- The pancreas ramps up insulin production to compensate, keeping blood sugar in the normal range.
- Blood sugar only begins to rise later, once the pancreas can no longer keep up — this is when pre-diabetes and eventually type 2 diabetes emerge.
This means a patient can feel the effects of insulin resistance — such as fatigue, weight gain, brain fog, or cravings — for years while their doctor’s glucose test shows nothing unusual.
The Right Test to Ask For
- Standard test: Fasting glucose — measures blood sugar levels, misses early insulin resistance.
- Recommended test: Fasting insulin test — directly measures circulating insulin levels.
- If fasting insulin is higher than normal, this confirms insulin resistance is present, regardless of blood sugar readings.
- Dr. Berg recommends patients specifically request this test from their doctor, as it is not part of routine blood work for most people.
Why This Window Matters
The stage where insulin is elevated but glucose is still normal represents a critical intervention window. Catching insulin resistance at this point — before blood sugar dysregulation sets in — allows for earlier lifestyle changes and a better chance of reversing the condition before it progresses further.