Summary: Fasting blood glucose is a result of your liver making glucose when you aren’t eating.  A high level may be an early indicator of possible insulin resistance.  You can lower your fasting blood glucose levels through healthy eating.

Q: When I got my recent labs drawn I noticed that my blood glucose measurement was 102 mg/dL.  But I was on a 12 hour fast and didn’t eat any sugar.  Why would it be that high?

A: Even though you were fasting your body is still producing glucose for energy all on it’s own through a process called gluconeogenesis.

Essentially, your body sends signals to your liver that it is no longer getting it’s energy source (glucose) from it’s food.  A metabolic switch – a protein called CREB – is what we believe turns this gluconeogenesis switch on.  This is your body’s adaptation to when humans used to have to go extended periods of time without getting reliable energy sources.

So, your liver is now making glucose to supply your energy needs.

But that still doesn’t answer why your glucose levels were outside the normal limits for fasting glucose levels.

While there is no definitive answer, the most likely answer is slight insulin resistance.

One of the things that will turn off the gluconeogenesis from fasting is when you eat food.  Insulin sends a signal to shut down gluconeogenesis.  If it didn’t your sugars would rise too high.

While your sugars aren’t dangerously high it is a bit of cause for concern.  And, as you can see from the pathway above, is probably linked to a slight degree of insulin resistance.  Your cells simply aren’t recognizing or sensitive enough to the insulin and thus aren’t down regulating gluconeogenesis like they should be.

Normalizing Fasting Blood Glucose Levels

I may have written about this before but I have a strong family history of diabetes.  At one point in pharmacy school I failed a glucose tolerance test and was told I was pre-diabetic.  At the time it probably didn’t scare me enough but I eventually figured out that I had to severely limit my sugar intake (primarily through processed foods).

As I have done that I have managed to get better and better fasting blood sugar readings.  While mine are still at the high end of normal (low 90’s) it’s much better than what it used to be.  Which should give you hope as you really aren’t super-high yet.  It can still be managed through diet.

I’d encourage you to go to my healthy eating section and start there.  I basically have chronicled some of the things I’ve done.  But the main point is eat natural foods and limit – or eliminate entirely – processed foods and over time you’ll find your fasting blood glucose levels dropping.