Living with diabetes comes with a wide range of experiences, one of which is the Somogyi Effect - A phenomenon that mainly affects those on insulin therapy.

According to the Somogyi effect theory, if insulin decreases blood sugar excessively, it may prompt the release of hormones, causing a rebound increase in blood sugar levels. However, this theory is subject to many controversies, given that many recent findings dispute it.

Let's explain the intricacies of the Somogyi Effect, exploring its causes, controversies, symptoms, complications, treatments, and prevention strategies.

Key Facts

  • The Somogyi effect is a complex response that affects diabetic patients. It causes high blood sugar in the morning after overnight low blood sugar, especially in those who use insulin.
  • The Somogyi effect is different from the dawn phenomenon: The former results from nocturnal hypoglycemia, which is more common in insulin users, while the latter is a natural rise in blood sugar related to circadian rhythm and affects a broader population.
  • There are debates as to whether the Somogyi effect truly causes morning hyperglycemia. Research suggests nocturnal hypoglycemia leads to morning hypoglycemia, not hyperglycemia. Studies have also linked insufficient insulin before bedtime to morning hyperglycemia. This implies that other factors (unrelated to the Somogyi phenomenon) may influence blood sugar changes in diabetes.

What is the Somogyi Effect?

The Somogyi effect, also known as "posthypoglycemic hyperglycemia," is a phenomenon that affects diabetic patients, particularly those on insulin therapy. The condition is named after the Hungarian-born professor and biochemist Michael Somogyi, who first described it in the 1930s.

This complex physiological response can have significant implications for diabetes management. It causes people to wake up in the morning with high blood sugar after taking insulin the previous night. Some experts believe that the early morning hyperglycemia caused by the Somogyi effect is a rebound effect of overnight hypoglycemia.
A Graph Showing The Blood Glucose Level Trend With The Somogyi Effect

The Somogyi Controversy

While people with diabetes can experience high blood sugar in the morning hours, there is little or no evidence the Somogyi effect causes this. In fact, research involving patients with Type 1 Diabetes indicated that nocturnal hypoglycemia is typically linked to early morning hypoglycemia rather than hyperglycemia.

Another study found that people are likely to wake up with high blood sugar when they don't take enough insulin before bedtime, contrary to the Somogyi effect theory.

In real-life situations at the doctor's office, it's noticed that when people have low blood sugar at night, they usually don't wake up with high blood sugar in the morning. This goes against the idea of the Somogyi phenomenon causing high blood sugar in the morning - meaning that other factors might be involved in how blood sugar levels change for people with diabetes.

How Does the Somogyi Effect Differ From the Dawn Phenomenon?

Often mistaken for each other, the Somogyi effect and the dawn phenomenon are similar responses to changes in blood sugar levels, especially overnight.

The Somogyi effect results from low blood sugar at night, often caused by too much insulin. This triggers a rebound of high blood sugar in the early morning.

On the other hand, the dawn phenomenon is a natural rise in blood sugar in the early morning related to the body's circadian rhythm.

While the Somogyi effect is more common in diabetic people using insulin therapy, the dawn phenomenon can affect a broader range of individuals, even those who do not have diabetes. However, people without diabetes may not notice the impact of the dawn phenomenon because they have enough insulin response to adjust their bodies naturally.

In practice, the best way to tell the difference between the Somogyi and dawn phenomenon is to monitor blood sugar levels at bedtime, around 2 AM to 3 AM, and during the usual wake-up time for several nights. Using a continuous glucose monitor throughout the night can also provide valuable insights.

If the blood sugar level is low from 2 AM to 3 AM, it could be the Somogyi effect. However, if the blood sugar level is normal or high at that time, it is more likely attributed to the dawn phenomenon.

What Triggers the Somogyi Effect?

While research has disproved this in practice, the Somogyi effect theory suggests that if your blood sugar drops too low during the night due to injected insulin, your body releases hormones like adrenaline (epinephrine), cortisol, growth hormone, and glucagon.

These hormones increase blood sugar by prompting your liver to release more stored glucose. In diabetes, insufficient insulin means the excess glucose isn't corrected, keeping blood sugar high. This phenomenon doesn't impact those without diabetes as their bodies naturally regulate blood sugar levels.

That said, any of the following likely triggers the Somogyi effect:

  • Eating little or no food at night
  • Excessive nighttime insulin
  • Nighttime low blood sugar levels
  • Activation of counterregulatory hormones like glucagon, cortisol, and epinephrine

Identifying the Symptoms of the Somogyi Effect

If you are using insulin to manage diabetes, then it's essential to know what the symptoms of the Somogyi effect feel like. This will help you manage the situation better and know when to visit your doctor.

Here are some symptoms that may suggest the occurrence of the Somogyi Effect:

  • Elevated blood sugar levels in the morning despite having experienced low blood sugar during the night
  • Excessive sweating at night
  • Persistent morning headaches
  • Increased morning hunger
  • Too much morning urination
  • Morning fatigue, dizziness, and confusion
  • Dry mouth and thirst

NOTE: These symptoms alone may not conclusively indicate the Somogyi effect. Regular monitoring of blood glucose levels, especially in the morning and during the night, is crucial for a more accurate assessment. If you observe these symptoms consistently, you should consult your doctor for further action.

Diagnosing the Somogyi Effect

Diagnosing the Somogyi effect can be challenging as it is not a common cause of high blood sugar in the morning. Recent studies have even disproved its existence. Therefore, healthcare providers may find it tasking to diagnose the condition definitively.

If you frequently experience morning hyperglycemia and its symptoms, your doctor will assess your blood sugar readings over time, preferably through continuous glucose monitoring (CGM) for an accurate evaluation.

If you don't use a CGM, you may be asked to check your blood sugar more frequently, including after dinner, before bedtime, between 2 AM and 3 AM, and upon waking. A low blood sugar reading between 2-3 AM and a high blood sugar reading when you wake up may mean you have the Somogyi effect.

What are the Possible Complications of the Somogyi Effect?

The Somogyi Effect, though not universally accepted, is linked to potential complications if not managed properly. These complications include poor blood sugar control, leading to consistent hyperglycemia and an increased risk of overnight hypoglycemia.

Consistent hyperglycemia can lead to increased HbA1c levels. High HbA1c levels over many months or years can result in conditions like diabetic retinopathy, nephropathy, neuropathy, and cardiovascular disease.

On the other hand, hypoglycemia due to the Somogyi effect happens when blood glucose levels fall below 70 mg/dl while sleeping at night. Restless and irritable sleep, accompanied by hot, clammy, or sweaty skin, trembling or shaking, and sudden changes in breathing, such as rapid or slow breaths, indicate nighttime hypoglycemia. You may also experience racing heartbeats or nightmares that wake you up suddenly. Since it's possible not to experience any of the symptoms listed above when your blood sugar drops too low at night, we recommend checking your levels at midnight, even without any visible signs. It's essential to consult your doctor once you notice a consistent overnight low blood sugar, as this can be potentially life-threatening.

Treatment and Mitigation Strategies

Mitigating the Somogyi effect involves vigilant blood sugar monitoring, especially over the night, to identify patterns. After assessing your overnight blood sugar patterns, your healthcare provider will guide you on adjustments to prevent elevated morning blood sugar levels.

Some of the possible changes your doctor may suggest include,

  • Changing the type of food you eat in the evening. Your doctor may suggest you eat a snack with your nightly insulin dosage to prevent blood sugar fluctuations.
  • Adjusting the time of your evening exercise. You may be required to exercise long before bedtime to reduce the risk of nocturnal hypoglycemia, which can lead to morning hyperglycemia.
  • You may require diabetes medication adjustments or entirely change your insulin type. Your doctor may prescribe a type of insulin called NPH, which becomes most effective six to eight hours after each dose.
  • You may need an insulin pump for more efficient and timely dosing.
  • Your doctor may also recommend investing in a Continuous Glucose Monitor (CGM). This monitor tracks glucose levels and provides alerts for high or low levels.


The Somogyi Effect poses a challenge for people with diabetes and can lead to fluctuating blood sugar levels in the morning. Pay attention to signs like recurring nocturnal hypoglycemia and morning hyperglycemia, and work with your doctor to adjust your diabetes management routine accordingly.

Exploring strategies like consuming a nightly snack with insulin, monitoring blood sugar in the middle of the night, or switching your insulin type can be part of a tailored approach your doctor could recommend.


At Diabetic Me, we are committed to delivering information that is precise, accurate, and pertinent. Our articles are supported by verified data from research papers, prestigious organizations, academic institutions, and medical associations to guarantee the integrity and relevance of the information we provide. You can learn more about our process and team on the about us page.

  1. MyHealth Alberta Dawn Phenomenon and the Somogyi Effect
  2. Johns Hopkins Medicine Hypoglycemia: Nocturnal
  3. National Library Of Medicine Nocturnal hypoglycaemias in type 1 diabetic patients: what can we learn with continuous glucose monitoring?
  5. National Library Of Medicine Circadian clock, diurnal glucose metabolic rhythm, and dawn phenomenon
  6. National Library Of Medicine The insulin-antagonistic effect of the counterregulatory hormones
  7. American Diabetes Association High Morning Blood Glucose
  8. National Library Of Medicine Somogyi Phenomenon

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About the Author

Ely Fornoville

Hi, I'm Ely Fornoville, and I am the founder of Diabetic Me. Being a type 1 diabetic since 1996, I developed a passion to help people learn more about diabetes. I write about diabetes and share stories from other diabetics around the world. I currently use a Medtronic Guardian 4 CGM and a MiniMed 780G insulin pump with Humalog insulin.

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