What is the dawn phenomenon that some people with diabetes experience? Can anything be done about it?

The dawn phenomenon is an early-morning rise in blood sugar, also called blood glucose, in people with diabetes. The dawn phenomenon leads to high levels of blood sugar, a condition called hyperglycemia. It usually happens between 4 a.m. and 8 a.m.

The cause of the dawn phenomenon isn't clear. Some researchers believe the overnight release of certain hormones that happens naturally increases insulin resistance. That causes blood sugar to rise. The hormones are called counter-regulatory hormones because they have an effect that opposes the effect of insulin. They include growth hormone, cortisol, glucagon and epinephrine.

High blood sugar in the morning may be caused by:

  • Not getting enough insulin the night before.
  • Not getting the right dose of diabetes medicine the night before.
  • Eating a snack with carbohydrates in it at bedtime.

If your blood sugar is consistently higher than it should be in the morning, talk to your health care provider. Your provider may suggest that you check your blood sugar once during the early-morning hours for a few days in a row. Or you might use a continuous glucose monitor to keep track of your blood sugar level as you sleep. That information helps your health care provider confirm if you have the dawn phenomenon or if there could be another reason for high morning blood sugar.

What you can do

To help you prevent or correct high blood sugar in the morning, your health care provider may suggest that you:

  • Avoid carbohydrates at bedtime.
  • Change your dose of diabetes medicine or insulin.
  • Switch to a different diabetes medicine.
  • Change the time when you take your medication or insulin from dinnertime to bedtime.
  • Use an insulin pump to give you extra insulin during early-morning hours.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

We use the data you provide to deliver you the content you requested. To provide you with the most relevant and helpful information, we may combine your email and website data with other information we have about you. If you are a Mayo Clinic patient, we will only use your protected health information as outlined in our Notice of Privacy Practices. You may opt out of email communications at any time by clicking on the unsubscribe link in the email.

Nov. 12, 2022 See more Expert Answers

See also

  1. Medication-free hypertension control
  2. A1C test
  3. Alcohol: Does it affect blood pressure?
  4. Alpha blockers
  5. Amputation and diabetes
  6. Angiotensin-converting enzyme (ACE) inhibitors
  7. Angiotensin II receptor blockers
  8. Anxiety: A cause of high blood pressure?
  9. Artificial sweeteners: Any effect on blood sugar?
  10. Bardet-Biedl syndrome (BBS)
  11. Bariatric surgery
  12. Beta blockers
  13. Beta blockers: Do they cause weight gain?
  14. Beta blockers: How do they affect exercise?
  15. Biliopancreatic diversion with duodenal switch (BPD/DS)
  16. Blood glucose meters
  17. Blood glucose monitors
  18. Blood pressure: Can it be higher in one arm?
  19. Blood pressure chart
  20. Blood pressure cuff: Does size matter?
  21. Blood pressure: Does it have a daily pattern?
  22. Blood pressure: Is it affected by cold weather?
  23. Blood pressure medication: Still necessary if I lose weight?
  24. Blood pressure medications: Can they raise my triglycerides?
  25. Blood pressure readings: Why higher at home?
  26. Blood sugar levels can fluctuate for many reasons
  27. Blood sugar testing: Why, when and how
  28. Bone and joint problems associated with diabetes
  29. Pancreas transplant animation
  30. Caffeine and hypertension
  31. Calcium channel blockers
  32. Calcium supplements: Do they interfere with blood pressure drugs?
  33. Can whole-grain foods lower blood pressure?
  34. Central-acting agents
  35. Choosing blood pressure medicines
  36. COVID-19: Who's at higher risk of serious symptoms?
  37. Diabetes
  38. Diabetes and depression: Coping with the two conditions
  39. Diabetes and exercise: When to monitor your blood sugar
  40. Diabetes and heat
  41. 10 ways to avoid diabetes complications
  42. Diabetes diet: Should I avoid sweet fruits?
  43. Diabetes diet: Create your healthy-eating plan
  44. Diabetes foods: Can I substitute honey for sugar?
  45. Diabetes and liver
  46. Diabetes management: How lifestyle, daily routine affect blood sugar
  47. Diabetes symptoms
  48. Diabetes treatment: Can cinnamon lower blood sugar?
  49. Using insulin
  50. Diabetic Gastroparesis
  51. Diuretics
  52. Diuretics: A cause of low potassium?
  53. Erectile dysfunction and diabetes
  54. High blood pressure and exercise
  55. Exercise and chronic disease
  56. Fatigue
  57. Free blood pressure machines: Are they accurate?
  58. Frequent urination
  59. Gastric bypass (Roux-en-Y)
  60. Gastric Bypass Complications
  61. Gastric bypass diet
  62. Gastric Bypass Surgery: One Patient's Journey
  63. Home blood pressure monitoring
  64. Glucose tolerance test
  65. Glycemic index: A helpful tool for diabetes?
  66. Weight-loss surgery
  67. Hemochromatosis
  68. High blood pressure (hypertension)
  69. High blood pressure and cold remedies: Which are safe?
  70. High blood pressure and sex
  71. High blood pressure dangers
  72. What is hypertension? A Mayo Clinic expert explains.
  73. Hypertension FAQs
  74. Hypertensive crisis: What are the symptoms?
  75. Insulin and weight gain
  76. Isolated systolic hypertension: A health concern?
  77. Kidney disease FAQs
  78. L-arginine: Does it lower blood pressure?
  79. Late-night eating: OK if you have diabetes?
  80. Low-phosphorus diet: Helpful for kidney disease?
  81. Medications and supplements that can raise your blood pressure
  82. Menopause and high blood pressure: What's the connection?
  83. Pancreas transplant
  84. Picnic Problems: High Sodium
  85. Pulse pressure: An indicator of heart health?
  86. Reactive hypoglycemia: What can I do?
  87. Resperate: Can it help reduce blood pressure?
  88. Sleep deprivation: A cause of high blood pressure?
  89. Sleeve gastrectomy
  90. Statins
  91. Stress and high blood pressure
  92. Unexplained weight loss
  93. Vasodilators
  94. Vegetarian diet: Can it help me control my diabetes?
  95. Biliopancreatic diversion with duodenal switch
  96. How to measure blood pressure using a manual monitor
  97. How to measure blood pressure using an automatic monitor
  98. What is blood pressure?
  99. Can a lack of vitamin D cause high blood pressure?
  100. Weight Loss Surgery Options
  101. White coat hypertension
  102. Wrist blood pressure monitors: Are they accurate?