Many people who are new to monitoring their blood glucose levels are alarmed to observe a spike in blood sugar in the early morning, typically between 3 and 8 am, before they’ve had any food. Naturally, patients wonder if this might mean they’re diabetic or have some other health condition. The good news is that while this effect is most common in people with insulin resistance, it also occurs in perfectly healthy individuals.

If you only have high blood sugar in the morning before eating, it may result from:

• 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.

To reduce the spike only if you’re not insulin resistant and don’t have diabetes:

• Aim for 6 to 8 hours of sleep each night: getting enough sleep can help reduce cortisol.

• Reduce your overall carbohydrate intake close to bedtime by avoiding carb-rich late night snacks.
• If you’re going to have a high-carb dinner, try to eat earlier in the evening, preferably 4 hours prior to bedtime.
• Get some light to moderate activity in the evening about an hour after dinner.
• Don’t delay breakfast: while you should aim for a lower carb breakfast since insulin resistance is greater in the morning, eating food early in the morning can help release insulin which can lower blood glucose.

An important safety warning:

If you have diabetes, it is important to work to reduce your overall carbohydrate intake in the evenings only with medical supervision. Reducing your intake of carbohydrates can decrease blood glucose as well as lower blood pressure. Consult with a physician to help safely adjust any medications you’re taking so that your blood glucose or blood pressure don’t drop too significantly. Both hypoglycemia (low blood sugar) and hypotension (low blood pressure) can be very dangerous.

The science behind it

Although the exact underlying causes of the dawn phenomenon are still unclear, we know that hormones play a large part. These hormones follow a circadian rhythm, or a daily cycle, and increase during our waking hours, the early morning.

The hormones that promote glucose release into the blood include:

• Epinephrine: more commonly known as adrenaline or the “fight or flight” hormone, increases blood flow to the muscles
• Cortisol: Known as the “stress hormone”
• Glucagon: signals the liver to release glucose into the blood
• Growth Hormone: repair and regeneration

Insulin is the most well-known hormone impacting blood sugar. When blood glucose rises, insulin is released and helps move glucose out of the blood and into cells for immediate energy use or storage.

Throughout the night, two key processes occur in the liver that result in the release of glucose into the bloodstream which contribute to elevated morning pre-prandial blood glucose levels:

1) Glycogenolysis, the breakdown and release of glycogen (the stored form of glucose)

2) Gluconeogenesis, the creation of glucose from components of protein or fat.

For patients with diabetes:

People who take insulin may also experience a spike in blood sugar in the morning, but for a different reason. If you manage your diabetes with insulin, you may experience something called the Somogyi Effect if you skip a meal or snack before bed or take too much or too little insulin at night. This occurs when your blood glucose lowers overnight, and then “rebounds” in the morning.

The Somogyi effect is generally considered to result from inconsistencies or inadequate diabetes management. Consult your doctor to determine if you’re experiencing the Somogyi effect and need adjustments to your schedule or the dawn phenomenon. As a general rule, if your blood sugar is low around 2-3 AM, you’re likely experiencing the Somogyi effect. If it’s normal or high at this time, the morning spike will often result from the dawn phenomenon.

If you have type 2 diabetes and take only certain diabetes medications like metformin, you should not experience the Somogyi effect.