Are high or low morning glucose levels normal?

Are high or low morning glucose levels normal?
  • Typical morning glucose (blood sugar) levels range between 70-99 mg/dl (3.9-5.5 mmol/L) in healthy adults.
  • If you notice morning glucose levels that are higher or lower than this range, it could be a normal response to what you ate the night before, sleep patterns, or stress. It could also be attributed to what’s known as the “dawn phenomenon” when blood sugar levels naturally rise in the early morning.
  • Continuous glucose monitors (CGMs) like Lingo give valuable insight into your metabolic health. Lifestyle and food choices can be modified to help you achieve steady morning glucose levels and optimal sleep.

When you think of sleep, you may think of complete rest and that the systems in your body shut down. However, sleep is a complex process that involves various stages and functions including glucose and energy metabolism, all controlled by the circadian rhythm. (1) 

Observing higher or lower glucose levels in the morning can be related to circadian rhythm or lifestyle habits and food choices surrounding sleep.

The connection between sleep and glucose levels

Glucose and sleep have a significant impact on each other. (2) High spikes and low crashes from the day can disrupt sleep, just as a poor night’s sleep worsens your ability to process glucose the following day. 

High blood sugar in the morning, even if you don’t have diabetes, may reflect what you ate at your evening meal, if you had any alcohol, are stressed, or the quality and duration of your sleep.

What causes higher glucose levels in the morning?

  • A large, late meal within 2-3 hours or less of trying to fall asleep
  • Alcohol, especially sugary mixed drinks, within 2-3 hours of bed 
  • Stress
  • Short sleep duration
  • Poor sleep quality


In the above scenarios, normal physiological processes that occur at night are disturbed as the body is working hard to metabolise a late meal, large amount of carbs or alcohol, or unable to fully rest due to stress. 

In approximately 50% of people with diabetes, the “dawn phenomenon” is a high blood sugar level in the early morning, generally between the hours of 4:00 a.m. to 8:00 a.m. (3) This rise is caused by insulin’s inability to properly act on the release of stored and new glucose from the liver into the blood. While commonly observed in individuals with diabetes, the use of CGMs have revealed that the dawn phenomenon can be experienced by individuals without diabetes, too.   

What causes lower glucose levels in the morning?

Alternatively, if you eat a lower-carb diet or don't eat many carbs in your evening meal, you may notice lower glucose levels in the morning. Alcohol late at night can also cause delayed overnight lows, which might show up after you fall asleep.

Why does sleep spike or lower my glucose levels? 

It’s not sleep per se, but usually meals or activities that take place before you go to sleep that are still being processed overnight. 

When you use a continuous glucose monitor like Lingo, you may notice your glucose starts to rise in the morning before you even wake up. This is normal and can be attributed to the metabolic processes governed by circadian rhythm, which is the internal clock in the body. When it’s time to wake up, your body temperature begins to rise, along with cortisol and glucose levels. These are all standard functions that tell your body it’s time to wake up.

What should my glucose levels be in the morning?

After an overnight fast, typical glucose levels in healthy individuals are less than 99 mg/dL (milligrams per decilitre) or 5.5 mmol/L (millimoles per litre), with more optimal levels landing in a tighter range, between 70-90 mg/dL (3.9-5.0 mmol/L). 

If your morning glucose level is above 99 mg/dL (5.5 mmol/L), it could be a totally normal, temporary response that is related to your meal and drink choices the night before, your total sleep time or sleep quality, or other lifestyle factors like stress. 

Using a product like Lingo enables you to have insight into how different behaviours impact your glucose. If your morning glucose is consistently elevated higher than the healthy range or changes significantly from what’s typical for you, talk to your doctor about what that may mean for you. 

What can I do to manage my morning glucose levels?

Lifestyle habits you can implement that may improve sleep quality and manage morning glucose levels include:

  • Close the kitchen and finish eating 2-3 hours prior to bedtime.
  • Avoid alcohol, especially soon before going to sleep.
  • Walk for 20 minutes after eating dinner.
  • While some studies show high glycaemic foods may help you fall asleep, (4) avoid large, high-carb meals that your body may still be trying to process overnight.
  • Adopt a wind-down nightly routine to minimise stress levels for quality sleep.
  • Exercise regularly: aim to meet your step goal most days of the week, achieve 150 minutes of aerobic exercise, and strength train at least 2 days per week


A final note from Lingo

Sleep and glucose are closely impacted by each other, and the relationship between the two is complex. Lifestyle habits, food, and sleep can all affect your morning glucose levels. 

By using a continuous glucose monitor like the Lingo biosensor, you can better understand how these factors play into your glucose levels and take charge to retrain your metabolism.

October 23, 2023


  1. Poggiogalle E, Jamshed H, Peterson CM. Circadian regulation of glucose, lipid, and energy metabolism in humans. Metabolism. 2018 Jul;84:11-27.
  2. Briançon-Marjollet A, Weiszenstein M, Henri M, Thomas A, Godin-Ribuot D, Polak J. The impact of sleep disorders on glucose metabolism: endocrine and molecular mechanisms. Diabetol Metab Syndr. 2015 Mar 24;7:25.
  3. Carroll MF, Schade DS. The dawn phenomenon revisited: implications for diabetes therapy. Endocr Pract. 2005 Jan-Feb;11(1):55-64.
  4. Afaghi A, O'Connor H, Chow CM. High-glycemic-index carbohydrate meals shorten sleep onset. Am J Clin Nutr. 2007 Feb;85(2):426-30.

Metabolic change is possible

Sign up and receive scientifically proven tips, strategies, and insights to supercharge your metabolism.
Email me personalised regular news, content and exclusive offers. I will receive an email from Lingo to confirm my email address. I consent to the use of my personal data for marketing purposes. Please refer to the Lingo Privacy Notice regarding your rights and for additional details.