Blood Sugar 64 mg/dl — Too Low? What It Means

A 64 after a night of drinks

Alcohol is one of the most common reasons for an unexpected low, and the timing catches people out. The reading of 64 mg/dl often turns up not at the bar but hours later, overnight or the next morning, long after the last glass. Readers with diabetes who use insulin or sulfonylurea tablets are most at risk, but heavy drinking on an empty stomach can push glucose down in people without diabetes as well.

A 64 is below 70 and counts as a low, so treat it the usual way with fast sugar before anything else. Then it helps to understand what the alcohol was doing.

Why the liver stops topping up your glucose

Between meals and overnight, your liver keeps blood glucose steady by releasing sugar from its stores and by making new glucose from other building blocks. Breaking down alcohol is a job the liver puts first, because alcohol is a toxin. While it is busy with that, its glucose output falls, especially the part that makes new glucose.

So after drinking, the safety net that normally catches a falling number is weaker. Add insulin still working from dinner, an evening of dancing, or a skipped meal, and glucose can slide into the 60s or lower while you sleep. Beer and sweet cocktails may raise glucose at first because of their carbohydrates, which makes the later fall even less expected.

People without diabetes are not completely protected. A long night of drinking with little or no food, particularly after a day of exercise, can empty the liver’s glucose stores and leave nothing to release. This is one reason young people, and anyone who drinks heavily on an empty stomach, occasionally end up in the emergency room with a low.

A low that looks like being drunk

Slurred speech, unsteady walking, confusion and drowsiness are signs of a low and also signs of too much alcohol. Friends, bar staff and even emergency crews can mistake one for the other. That is a real safety problem, because someone with a severe low needs sugar, not to be left to sleep it off.

• Wear or carry something that says you have diabetes if you take insulin or a sulfonylurea.
• Tell at least one person you are with what a low looks like and what to do.
• Check before bed, and if the number is on the low side, eat a snack with some starch and protein first.
• Set an alarm to check in the night or early morning after heavier drinking, or use a CGM low alert if you have one.

Next-morning lows and how to plan around them

The risk can last into the following day, especially after several drinks. Do not skip breakfast after a night out, and check before driving. People without diabetes who find a low the morning after drinking should note how much they drank and whether they ate; if it happens again, mention it to a doctor.

Common advice for drinking more safely with diabetes includes having alcohol with food rather than instead of it, choosing lower-alcohol drinks, alternating with water, and never using alcohol to replace a meal on insulin days. Your care team may also suggest a lower evening insulin dose on nights you drink; only change a dose with their guidance. More on the bigger picture is on what affects blood sugar.