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Insulin resistance
Hi B. Can you please share what to look for to know if someone has insulin resistance? What are the expected numbers on tests like GTT, fasting insulin, fasting glucose, C peptide levels etc? -
2 Replies
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Hey ,
Fasting Insulin
I usually consider fasting insulin between the 2-6 uIU/ml optimal. (The typical reference range is: 2-25)OGTT (Oral Glucose Tolerance Test)
The glucose tolerance test (usually done with 75 gram of glucose – not with food) gives back a curve.
• The curve is optimal when blood sugars spike in the first 30-60 minutes and return to normal after 2-2.5 hours. The highest value should not exceed the renal threshold (160-180 mg/dl). This means basically there should be no glucose in the urine afterwards.
• With early insulin resistance, we can see blood glucose drop after 2-2.5 hours below fasting levels. In this stage blood sugar levels can still appear normal, but there is already a more robust insulin response. In this stage, insulin is winning and blood glucose is dropping below fasting levels
• In a more advanced stage, blood sugars rise less quickly (the blood sugar peaks between 1-1.5 hours). The highest blood sugar level exceeds the renal threshold. The blood glucose level does not return to normal after 2.5 hours.Just remember that a blood glucose meter can make errors. With mild unclear values, you wouldn’t want to evaluate only one curve(Because glucose is a reflection of insulin). For that reason, I usually recommend doing an oral insulin tolerance test at the same time.
for both these tests, make sure if patients are on a ketogenic diet they raise their carb intake for a minimum of 3 days.
Fasting glucose
I consider optimal likely between 80-88 mg/dl. Above is evidence of insulin resistance.C-peptide
I consider optimal likely between 1-2 ng/ml (with a typical reference range of 1.0-4.2).I hope this helps!
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Hi – you can also find all of these optimal ranges and additional information in the Blood Sugar Regulation course in the “Testing Considerations” video here.
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