Discover 8 tips to manage and understand why your blood sugar rises at night.
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Diabetes never sleeps, and while you’re snoozing, your blood sugar can climb out of your target range.
“Your overnight blood sugar levels make up one-third of your next A1C,” says Ben Tzeel, CDCES, RD, and founder of Your Diabetes Insider. A1C is an estimate of your average blood sugar levels over the last several months. “There are 24 hours in a day and you spend about eight hours sleeping. If your blood sugar is usually high during those eight hours, you’ll definitely see the impact on your A1C.”
Overnight blood sugar fluctuations can mean interrupted sleep, a big impact on your A1C, and safety risks, too. Whether you have type 1 or type 2 diabetes, here are eight tips to help understand why your blood sugar goes up at night, and what you can do about it.
1. Avoid Slow-Digesting Meals
Nothing raises blood sugar levels like carbohydrates, especially refined and processed carbohydrates like the sugar and white flour often found in sweets and junk food. Passing on sweet, starchy foods before bedtime is an easy choice to help keep your blood sugars steady overnight.
But meals with more protein and fat — think pizza, lasagna, Chinese takeout, tacos, and burgers and fries — have a sneakier, slower effect on blood sugar levels, one that might not show up until you’ve gone to bed.
These foods contain so much dietary fat that it can significantly delay the full digestion of the carbohydrates in the meal. This means your blood sugar might be in your target range at 10 p.m. but spike wildly several hours later, when you’re sound asleep.
Watch out for meals that combine so much fat and starch. Opting for meals with plenty of nonstarchy veggies and lean protein increase the odds of steady and healthy overnight blood sugars.
2. Start Using a CGM
If you’ve been reluctant to use a continuous glucose monitor (CGM), it may be time. These devices stick to your skin and measure your blood sugar continuously, updating your smart phone with new data around the clock. For people who use insulin, CGMs can also sound low and high blood sugar alerts, waking you up before you’re in danger.
“A CGM can give you peace of mind,” explains Tzeel, who’s lived with type 1 diabetes for decades. “If you’ve been running your blood sugar higher at night because you’re afraid of hypoglycemia during your sleep, a CGM can be an alert system for your blood sugars while you sleep.”
A CGM also gives you data you can’t otherwise get. What’s really happening while you sleep? A CGM will tell you exactly when your blood sugar is rising or falling, giving you and your healthcare team the necessary data to adjust your medication doses and diabetes management plan. If you take a high fasting blood sugar measurement in the morning, a CGM can help tell you when your blood sugar began to rise — helping you isolate the cause.
3. Cope With Your Stress
Stress can cause high blood sugar levels, partially because stress hormones like cortisol raise blood sugar directly. People with chronic stress tend to have higher A1C levels and a higher incidence of diabetes complications.
It’s time to recognize that stress management is diabetes management, and that mental health issues are legitimate medical concerns that deserve treatment. A healthy lifestyle — eating well, staying hydrated, and exercising regularly — can help, but don’t be afraid to seek professional help if you need it.
4. Create Some Consistency in Your Evening Routine
It will be tough to identify why your blood sugar rises overnight if you have inconsistent habits in the evening.
“Diabetes loves routine,” says Tzeel. “The more familiar you are with what you’re eating, the more easily you can predict the impact it will have on your blood sugar, especially if you’re frustrated with blood sugar levels rising at night.”
The same goes for exercise.
“Particularly if you take insulin, pay close attention to when you exercise,” says Tzeel. “If you normally exercise in the morning, that can affect your insulin sensitivity and blood sugar levels for the next five or six hours. If you suddenly exercise in the evening one night, your sensitivity will hit while you’re sleeping.”
This doesn’t mean people with diabetes must follow a rigid routine every day, but you do want to be aware of your usual routine, and when you break from it. Your routine matters!
5. Adjust Your Diabetes Medications
If your blood sugars are out of your target range while you sleep, this can be a sign that your medication dosage might need to be recalibrated.
Blood sugar management is always a moving target. It’s important to regularly review your diabetes medication dosages with your medical team. Most people will need to to add medications over time.
If you take insulin, it’s especially important to make frequent adjustments. It’s easy to take too much or too little rapid-acting insulin for a meal. Work with your team to fine-tune your daily doses and dosing ratios. These numbers often need to be tweaked as you age, or when there are changes in your weight, activity level, or nutrition habits.
6. Use Reminders and Alarms
Do you have trouble remembering to take your diabetes medications? Set some reminders!
Your diabetes medications can’t help keep your blood sugar healthy if you forget to take them. Whether it’s a Post-it note, a smartphone alarm, or the latest virtual assistant technology, many people with diabetes rely upon reminder systems to make sure they never miss a dose.
7. Start an Evening Exercise Routine
The evening is a great time to exercise. Exercise usually lowers blood sugar levels — a workout increases insulin sensitivity and causes your muscles to take up the glucose in your bloodstream — making it a potent tool for overnight diabetes control.
“If you’re trying to improve your overnight blood sugar levels, a little workout session in the evening could help,” says Tzeel.
Be cautious, though: If exercise causes your blood sugar to drop too low, it becomes a problem. This is usually an issue for people who use insulin or sulfonylureas.
“There are a few things you can do to prevent lows after working out in the evening,” says Tzeel. “First, if you take insulin, you can work with your healthcare team to adjust your insulin doses on the nights you exercise so you don’t dip low.”
“If you don’t take insulin, try having a little protein or fat before bed to stabilize blood sugar levels,” says Tzeel. Keep in mind the carbohydrate content that might accompany that fat or protein. “This also helps with muscle recovery if you’re lifting weights.”
When you’re not drinking enough water, your body releases glucose-spiking stress hormones and your glucose tolerance declines. The problem is even more serious if an illness has caused you to experience vomiting, diarrhea, or loss of appetite, all of which accelerate dehydration and raise the risk of acute hyperglycemia.
Getting enough water every day is a must for anyone with diabetes. Not sure how much you should be drinking every day? Try a hydration calculator.
The Takeaway
When your blood sugars rise overnight, it’s a hint that you may need to adjust your medication regimen or change your diet and exercise habits.
Setting a consistent and healthy evening routine, including wholesome food and exercise, can go a long way to preventing blood sugar rises after bedtime.
Pay close attention to your blood sugar, ideally with a continuous glucose monitor (CGM), and share your notes with your healthcare provider, who can help you troubleshoot those stubborn high glucose levels.
Elise M Brett, MD, is a board-certified adult endocrinologist. She received a bachelor's degree from the University of Michigan and her MD degree from the Icahn School of Medicine at Mount Sinai. She completed her residency training in internal medicine and fellowship in endocrinology and metabolism at The Mount Sinai Hospital. She has been in private practice in Manhattan since 1999.
Dr. Brett practices general endocrinology and diabetes and has additional certification in neck ultrasound and fine-needle aspiration biopsy, which she performs regularly in the office. She is voluntary faculty and associate clinical professor at the Icahn School of Medicine at Mount Sinai. She is a former member of the board of directors of the American Association of Clinical Endocrinology. She has lectured nationally and published book chapters and peer reviewed articles on various topics, including thyroid cancer, neck ultrasound, parathyroid disease, obesity, diabetes, and nutrition support.
Ginger is a freelance writer and editor with a bachelor's degree in professional writing, and a background in cognitive coaching, video blogging, record-setting competitive powerlifting, personal training, Ashtanga yoga, and motivational speaking.
She lives in Vermont with a handsome husband, two daughters, and a loyal dog named Pedro.
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