A Bedtime Snack and Blood Sugar: Diabetes Questions & Answers

Q: Does a bedtime snack help or hurt the wake-up blood sugar reading?

A: Like most things having to do with diabetes, it depends. If you are not taking insulin, bedtime snacks can either cause your wake-up reading to be elevated or force your pancreas to produce extra insulin during the night to offset the effects of the snack — neither of which is a good thing.

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If you take insulin, a bedtime snack may be needed if your blood sugar tends to drop overnight. This is often a sign that your basal insulin dose (via injection or a pump) is a bit too high. Basal insulin’s job is to keep your blood sugar steady overnight. So if you’re dropping, you may be getting too much basal insulin. In this case, without a snack, you might wind up with low blood sugar in the middle of the night. And if you overeat or “rebound” from the low, your wake-up reading could wind up too high. So with basal insulin doses that are a bit too high, a snack at night may be necessary. However, it would be better to get the basal insulin dose set properly.

If your basal insulin dose is correct and your blood sugar holds steady through the night without a snack, a bedtime snack will make your blood sugar rise. A dose of rapid-acting insulin would likely be needed to offset the effects of the carbohydrates in the snack.

While we sleep, the body produces a hormone called leptin that curbs appetite. So if you’re trying to shed some body fat, a bedtime snack may be counterproductive. And since excess body fat leads to insulin resistance, all those extra bedtime snacks can lead to higher-than-desired blood sugars in the morning that persist around the clock.

Want to learn more about maintaining target blood sugar levels during sleep? Read “Exorcising the Specter of Overnight Hypoglycemia” and “The Dawn Phenomenon and Somogyi Effect: What You Can Do.”