Why does blood sugar rise overnight

For patients in whom the dawn effect is pronounced, a switch in nighttime basal insulin may be warranted. Taking the nighttime basal dose before bedtime instead of after dinner may help keep insulin levels from waning in the dawn hours. A switch from a long-acting basal insulin to one timed to peak in the early morning such as NPH may be considered.

The Somogyi Effect Another physiological cause of morning hyperglycemia is the Somogyi effect. Also known as rebound hyperglycemia or insulin-induced posthypoglycemic hyperglycemia, this phenomenon is named for the late Michael Somogyi, PhD, former professor of biochemistry at the Washington University and Jewish Hospital of St Louis, who first described it in a paper published in the Weekly Bulletin of the St.

Louis Medical Society. While the dawn effect occurs naturally in select individuals, the Somogyi effect is caused by administration of excessive insulin. If the blood sugar level reaches a dangerous low, the body reacts with an emergency release of counterregulatory hormones that increase glucose in the bloodstream. The patient is saved from a diabetic coma or death but awakens with hyperglycemia. The counterregulatory hormones continue to circulate in the body throughout the morning, causing insulin resistance that persists through breakfast and, in some patients, even through lunch.

Perplexed patients find that their breakfast and perhaps lunch bolus fails to bring their blood sugar level down. If you have persistently elevated blood sugar in the morning, checking your blood sugar once during the night — around 2 a.

Your doctor may recommend a number of options to help you prevent or correct high blood sugar levels in the morning:. There is a problem with information submitted for this request. Sign up for free, and stay up-to-date on research advancements, health tips and current health topics, like COVID, plus expert advice on managing your health.

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Mayo Clinic does not endorse any of the third party products and services advertised. A single copy of these materials may be reprinted for noncommercial personal use only. This content does not have an English version. This content does not have an Arabic version. See more conditions. Request Appointment. The dawn phenomenon: What can you do? Products and services. Approximately half of those with either type 1 or type 2 experience it.

If your insulin level falls too low overnight, your blood sugar rises. The reasons for the drop in insulin vary from person to person, but it most commonly occurs when your insulin pump settings provide too little basal background insulin overnight or if your long-acting insulin dose is too low. Insulin duration—how long the drug works in your body—also comes into play.

If you inject your long-acting insulin early, it may not last into the morning. Say you miss dinner or take too much insulin after your evening meal. Your blood sugar may fall too low overnight. Your body makes more glucose in order to compensate, and you wake up with high blood sugar. If a pattern of frequent morning highs emerges during your routine glucose monitoring, check your blood sugar levels at bedtime, in the middle of the night and first thing when you wake up to develop a better understanding of your glucose patterns.

Your readings will tell you and your doctor when your highs and lows occur and that, in turn, will help narrow the cause of the problem. If you have high blood sugars before you go to sleep, the elevated level can persist until morning. In the early morning hours, hormones such as the growth hormone and cortisol cause the liver to release glucose into the blood. At least having a reason to explain above target blood glucose levels in the morning is helpful; however, it can remain frustrating.

Managing the dawn phenonema is an ongoing research area. For those with type 2 diabetes starting basal insulin is believed to assist in reducing the production of glucose from the liver overnight. If you are already on insulin injections, it is important to consider the 3am blood glucose level before increasing the basal insulin further.

For people on an insulin pump, basal rates at that time of day can be increased. Lifestyle changes may also assist. Suggestions include evening exercise, eating less carb and more protein with the evening meal, and not skipping the breakfast meal.

Your diabetes team will be happy to assist you to troubleshoot out of target blood glucose levels. Join our community of over 33, people living with diabetes.

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