What should your blood sugar level be before bedtime?

Blood sugar target ranges can change not only throughout your lifetime, but also throughout a typical day!

For example, you might choose to have a higher blood sugar level before exercising or a lower blood sugar level before eating dessert. It all depends on the person.

But the question is often asked, what should be the blood sugar level before bedtime?

In this article, we’ll discuss the importance of having a safe blood sugar level before bed, what to do to achieve it, and other tips for better controlling your blood sugar in the evening.

What are normal blood sugar levels?

While this range is different for everyone, typically a person with diabetes aims for a blood sugar level of 70 to 130 mg/dL throughout the day, before meals.

The American Diabetes Association recommends a blood sugar level not higher than 180 mg/dL two hours after a meal. Work with your doctor to find out what the ideal range will be right for you and your health goals.

For example, for a pregnant woman, blood sugar control needs to be tighter, with fasting blood sugar levels between 70-100 mg/dl and blood sugar levels no higher than 140 mg/dl after meals.

For someone who struggles with hypoglycemic unawareness when they cannot detect or sense their own low blood sugar, the target blood sugar range may be slightly higher to avoid dangerous and spiraling low blood sugar.

However, your blood sugar target before bedtime is slightly different than during the day.


Why do bedtime blood sugar targets vary? 
Many people struggle with blood sugar levels during the night.  This is because we stay awake for 8 to 10 hours to make course corrections in the form of taking extra insulin or eating carbohydrates to avoid both high and low blood sugar! 
It can be difficult to eat an evening meal and then expect ideal blood sugar levels throughout the night.  And while high blood sugar levels at night are irritating and can make you sick (and may even contribute to diabetes complications in the long run), low blood sugar levels at night are very dangerous and should be avoided as much as possible . 
This is especially important if you struggle with hypoglycemia unawareness or if you don’t have a continuous glucose monitor (CGM), which can help detect low blood sugar and alert you if fast-acting glucose needs to be administered. 

What are the recommended blood sugar levels before bedtime? 
While your blood sugar target may be lower during the day, it is generally recommended not to go to bed with your blood sugar below 100 mg/dL, especially if you have active insulin (insulin that is still active in your bloodstream and so you’re more likely to fall low). 
You will need to treat most sugars below 100 mg/dL with a snack to make sure your blood sugar is stabilized for the duration of your sleep. 
This can help prevent dangerously low blood sugar levels overnight, especially if you take multiple daily injections (MDI) and/or don’t have a continuous glucose monitor (CGM). 
On the other hand, you don’t want to go to bed with blood sugar levels that are too high, as this can lead to dangerous hyperglycemia during sleep, setting you up for prolonged high blood sugar levels the next morning. 
Work with your doctor to see what works best for you, but typically any blood sugar level above 180 mg/dL at bedtime should be corrected with a bolus of insulin. 

Tips for stabilizing blood sugar before bedtime 
The following tips will help you stabilize your blood sugar before bed so you don’t drop too high or too low during the night. 
Preventing low blood sugar overnight

Have a bedtime snack that is full of both fat and protein as this will slow down the digestion of carbohydrates and stabilize glucose levels
If you exercise regularly, do so earlier in the day 
Eat a lower carb dinner to have less insulin on board before going to bed
Limit alcohol in general and especially right before bed as it can cause your blood sugar levels to drop
Lower basal insulin doses at night if you use an insulin pump
if you take multiple daily injections (MDI), take the long-acting dose in the morning so it’s not as strong overnight (or split it into mornings and evenings).  Consult your doctor before adjusting any insulin dose or timing of doses. 
Get a continuous glucose monitor (CGM) and set your low alarm higher than the one you treat low blood sugar at so you can wake up and adjust before you experience dangerous low blood sugar. 

Preventing high blood sugar levels overnight 

Eat a lower carb dinner to have fewer active carbs in your body before bedtime.
Eat dinner earlier in the evening and do not snack 1-2 hours before going to bed
Increase the amount of protein and fat in your dinner 
Take a 10-20 minute walk after dinner to help prevent postprandial glucose fluctuations 
Take a hot shower before going to bed;  the heat helps to stimulate insulin in the blood vessels and can help lower blood sugar levels 
Increase your daily basal rates or, if using an MDI, split your long-acting dose by taking half in the morning and half at bedtime so you’ll have extra insulin on board to combat nighttime highs 
Get a CGM and set a high alarm to be alerted when your blood sugar spikes while you sleep, and you can bolus and course adjust overnight if needed 


Conclusions
Managing blood sugar at night can be the hardest part of diabetes, simply because we’re sleeping!  But good nighttime blood sugar management starts with good blood sugar levels at bedtime. 
Blood sugar target ranges will vary from person to person, but it’s usually best not to have your blood sugar below 100 mg/dL at bedtime or above 180 mg/dL. 
Some strategies can help prevent low blood sugar levels at night, including lowering your basal rate or changing the timing of your insulin injections, eating a high-protein, high-fat snack before bed, and not exercising in the evening. 
Several strategies to help prevent high blood sugar levels at night include eating fewer carbohydrates at dinner time, eating dinner earlier in the evening, taking a short walk after dinner, taking a hot shower, and increasing your basal rates and/or changing your insulin doses. 
In either case, having a CGM that alerts you to high and low blood sugar levels before they become dangerous is critical to a more restful (and safer!) night’s sleep. 
Work with your doctor to find out what your ideal blood sugar level should be before bedtime and what tactics would be most appropriate to help you prevent both high and low blood sugar while you sleep. 
For more tips on managing your blood sugar at night, read our guide: How to avoid high blood sugar at night