Thursday, August 13, 2009

Alcohol Can Lower Fasting Blood Glucose

This topic has come up a few times recently so I thought I'd post about it.

Drinking alcoholic beverages can depress your fasting blood glucose levels. This can be beneficial, but it can also lead to a false sense of security about your glucose metabolism.


The ethanol in alcohol inhibits gluconeogenesis, which is the new (neo) making (genesis) of glucose (gluco). Gluconeogenesis occurs primarily in the liver and is one way your body supplies glucose to tissues during a fast, such as overnight.

So, if the only reading you're checking is fasting, or first thing in the morning, and it's below 100 mg/dl, and you think you're fine, double-check it with a few postprandials throughout the day. (A high HbA1c with low fastings could result from this effect.)

Here's one study:
Glycemic Effects Of Moderate Alcohol Intake Among Patients With Type 2 Diabetes: A Multicenter, Randomized, Clinical Intervention Trial, Diabetes Care, 2007

Participants (91 completed the study) had type 2 diabetes and received one of the following daily for 3 months (consumed at dinner):
  • 150 ml wine (about 5 ounces or a little more than 1/2 cup) (either Merlot or Sauvignon Blanc)
  • 150 ml nonalcoholic diet beer (control group)
  • In the wine group, fasting glucose dropped from 139.6 to 118.0 mg/dl.
  • The control group experienced no change, 136.7 to 138.6 mg/dl.
  • Those with the highest HbA1c levels had the greatest reductions.
  • Alcohol consumption had no effect on 2-hour postprandial glucose.
Of course, individuals vary. And not all studies show this effect, even though there's a biologically plausible mechanism.

Update: For those who are asking: A normal (conservative) postprandial blood glucose reading is below 140 mg/dl. You want to see your blood sugar getting below 140 at about 2 hours after you finish eating a meal.


Steve Parker, M.D. said...

Thanks for sharing this information.

Most of the medical establishment is dead set against their diabetic patients drinking alcohol in light to moderate amounts.

On the other hand, some of us believe the data that show longer lifespans and less cardiovascular disease in people who drink sensibly.

Compared to the general population, diabetics are prone to cardiovascular disease (heart attack and stroke) and premature death. May not alcohol (red wine in particular?) counteract this trend?

For diabetics who run a fasting glucose of 85, it's possible a glass of wine - according to the study at hand - could drop blood sugar levels dangerously low, e.g., down to 65 or less. Be careful.


Disclaimer: All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status. Always consult your personal physician before making any dietary or exercise changes.

Perovskia said...

Hmm.. I'm getting used to the term HbA1c levels; this is new to me. I'm used to hearing/seeing someone check their sugar with a glucose monitor and it reading a "5" or "6" or whatnot. Can HbA1c levels be checked with a glucose monitor? How does one check these? And what do you mean by 'postprandial'?

Bix said...

HbA1c, or Hemoglobin A1c, is generally the percentage of your hemoglobin that has glucose attached. An HbA1c of 6 means about 6% of the hemoglobin in your red blood cells (RBCs) is glycosylated (has glucose attached).

RBCs circulate for 3 or 4 months before they're broken down and replaced. During that time, hemoglobin in the RBC can bond with glucose in the bloodstream. If you have many glucose spikes, your HbA1c will be high. HbA1c is thus a marker of your blood glucose over a 3 or 4 month period.

You can't measure HbA1c with a standard blood glucose meter. It's usually measured as part of a blood work-up. There are some home kits you can buy, a little pricy and the accuracy is questionable.

Postprandial = after eating. Usually up to 2 hours.

Unknown said...

That was the best explanation of A1c that I heard. Better than my diabetes educator ever gave me. Thanks!!