When you use insulin therapy to control your diabetes, you need to measure your blood sugar levels several times a day. Depending on the results, you might take insulin to lower your blood sugar levels or have a snack to raise them.

The Somogyi effect or phenomenon happens when you take insulin before bed and wake up with high blood sugar levels.

According to the theory of the Somogyi effect, when insulin lowers your blood sugar too much, it can trigger a release of hormones that send your blood sugar levels into a rebound high. It’s thought to be more common in people with type 1 diabetes than type 2 diabetes.

Although high glucose in the morning does happen, there’s little evidence to support that the Somogyi effect theory is the explanation. But if you notice these symptoms, inconsistencies, or large changes in your blood sugar levels, speak with your doctor.

You may be experiencing the Somogyi effect if you wake up with high blood sugar levels in the morning and you don’t know why. Night sweats may be a symptom of this phenomenon.

The dawn phenomenon experience is similar to the Somogyi effect, but the causes are different.

Everyone experiences the dawn phenomenon to some extent. It’s your body’s natural reaction to hormones (cortisol, growth hormone, and catecholamine) that are released as morning approaches. These hormones trigger the release of glucose from your liver.

In most people, the release of glucose is tempered by the release of insulin. But when you have diabetes, you don’t produce enough insulin to lessen the release of glucose, and that causes your blood sugar levels rise.

If you have diabetes, you may use insulin injections to manage your blood sugar levels. When you inject too much insulin, or you inject insulin and go to bed without eating enough, it lowers your blood sugar levels too much. This is called hypoglycemia.

Your body responds to hypoglycemia by releasing hormones like glucagon and epinephrine. These hormones raise your blood sugar levels. Therefore, the Somogyi effect is sometimes referred to as the “rebound effect.”

The Somogyi effect is widely reported. But there’s little scientific evidence to support it.

It’s relatively easy to test for the Somogyi effect. For several consecutive nights:

  • Check your blood sugar just before bed.
  • Set an alarm to check it again around 3:00 a.m.
  • Test it again upon waking.

If your blood glucose is low when you check it at 3:00 a.m., it’s likely the Somogyi effect.

You can also ask your doctor about using a continuous glucose monitoring (CGM) system. Your doctor will insert a tiny glucose sensor under your skin. It sends information to a monitoring device that tracks your glucose levels and lets you know when levels are too high or too low.

If you have diabetes and experience the Somogyi effect, talk with your doctor. Discuss any recurring fluctuations, like high morning blood sugar levels. Ask how you can adjust your diabetes management routine to keep your blood sugar under control.

You may find that eating a snack with your nightly insulin dosage helps stop your blood sugar levels from dipping and rebounding. Your doctor may also recommend changes to your insulin regime.

For example, they might advise you to take less insulin at night or try a different type of insulin. Talk with them about setting a slightly higher, but still safe, target blood sugar level for bedtime.

If you think you may start to experience the Somogyi effect soon after increasing your nightly dose of insulin, it might be best to wake up in the middle of the night for a few nights to test your blood sugar levels. Increasing your insulin dosage gradually could also help.

Talk with your doctor to decide on the best plan for you. Your doctor may also encourage you to invest in a CGM system. This monitor tracks your glucose levels and uses alarms to let you know when your levels get too high or too low.

It’s important to talk with your doctor before adjusting your insulin regimen, particularly if you’re experiencing sharp blood sugar fluctuations.

Managing your diabetes takes practice and care. Learning how your body reacts to things like food, insulin, and exercise can make it easier.