What is an optimal fasting glucose level?
The short answer
Optimal fasting glucose starts at 70 mg/dL in one video and tops out at 80 mg/dL in another.
Most labs call fasting glucose high only above 99. So your report can call 90 normal while it sits above the optimal ceiling.
Sources disagree on optimal
“So, for fasting glucose, ideally, you're looking at 70 to 80. It doesn't mean if you're 81 that it's something you don't have to panic about it. It's going to fluctuate.”
Not every source agrees with that line.
“your fasting blood sugar should be between 70 to 90”
“I generally like to see the fasting glucose below 90 milligrams per deciliter”
What each range means
- under 70 mg/dL Most labs flag this as low
- under 70 mg/dL Below optimal
- 70–80 mg/dL Optimal“your fasting blood sugar should be between 70 to 90” Dr. Mark Hyman · 2:38 →
- 80–99 mg/dL Normal on most reports. Above optimal
- over 99 mg/dL Most labs flag this as high
What fasting glucose measures
The sugar in your blood after a night without food.
It is the most direct look at how well your body clears sugar with no food in the system.
Checked against MedlinePlus — Blood Glucose Test.
Why it matters, on the record
“glucose causes microvascular disease the insulin causes macrovascular disease they're both bad you need to control both of them”
Common questions
What is an optimal fasting glucose level?
70–80 mg/dL, from a quote on video (Dr. Florence Comite, 39:59).
What is a normal fasting glucose level?
Most US labs print 70–99 mg/dL. Your report grades you against that range. It exists to catch disease, not to describe your best.
What does your fasting glucose number mean?
On a typical lab range, under 70 mg/dL is low, 70 to 99 is normal and over 99 is high. Your own report prints its range next to your number, and that is the one your lab uses. The optimal range on this page comes with the quote behind it.
Is fasting glucose of 90 normal?
A typical lab range calls it normal. On video, the optimal ceiling is 80 mg/dL (Dr. Florence Comite, 39:59), so by that line it is high. Not every source agrees with that line.
Do the sources agree?
No. There is also a case for a different line: “your fasting blood sugar should be between 70 to 90” (Dr. Mark Hyman, 2:38)
What does the fasting glucose test measure?
The sugar in your blood after a night without food. It is the most direct look at how well your body clears sugar with no food in the system.