If you have diabetes, there are several reasons why your blood sugar may be high during the night — and therefore high the next morning. The most common causes are eating too many carbohydrates at bedtime and not taking enough diabetes medication, according to the Cleveland Clinic.
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But morning hyperglycemia (high blood sugar) can have other causes, including the Somogyi effect, sometimes called rebound hyperglycemia. Managing this effect often requires eating a small evening snack to keep blood sugar levels stable throughout the night.
Understanding High Blood Sugar at Night
Blood sugar, also called glucose, is the body's main source of energy. The body gets most of its glucose by metabolizing the carbohydrates in food, per Kaiser Permanente. For people with diabetes, their systems struggle to manage glucose correctly, leading to high blood sugar. But the treatment of diabetes can also cause low blood sugar (hypoglycemia).
"Some diabetes medications [like insulin] lower blood glucose levels during the night," Jo-Anne Rizzotto, a registered dietitian nutritionist and director of educational services at Harvard's Joslin Diabetes Center, tells LIVESTRONG.com. "But if blood sugar levels drop too low, the liver responds by releasing stored glucose." This nocturnal release of glucose can cause high blood sugar during the night and into the next morning, known as the Somogyi effect. The good news? "People with type 2 diabetes don't have this issue unless they're on [insulin or other] glucose-lowering medications," says Rizzotto.
The Somogyi effect should not be confused with the so-called "dawn phenomenon," another cause of high morning blood sugar, Rizzotto says. The dawn phenomenon is a product of human evolution; it occurs in all people and involves the body pumping out extra glucose in the early morning hours to get the body ready to wake up.
What to Eat to Maintain Blood Sugar Levels at Night
If you're hungry at night, eat a low-carb snack to keep your blood sugar from spiking. If you're managing the Somogyi effect, you'll likely need to include some carbohydrates to prevent low blood sugar and the resulting rebound hyperglycemia. Rizzotto says an evening snack should be eaten about two hours before bed.
Protein does not spike blood sugar or insulin levels, making it an ideal bedtime food choice. Protein also slows the body's ability to metabolize carbohydrates, according to a June 2015 systematic review published in Diabetes Care. The slower the body absorbs carbs, the less your blood sugar levels will rise. Smart high-protein options include a hard-boiled egg, tofu, low-fat yogurt or a few slices of low-fat deli meat, such as turkey.
Fats also play an important role in controlling blood sugar levels. According to the National Institute on Aging, they give the body energy without raising blood sugars. They also help the body absorb essential vitamins. Therefore, it's wise to include a small amount of healthy fat in your evening snack.
Healthy fats are found in low-fat cheeses, seeds, nuts, avocados and olive oil. But though these fat sources are nutritious, it's important that you enjoy them in moderation so as to avoid consuming too many calories and gaining weight. A healthy serving size for nuts, seeds and cheese is about an ounce, or 1 to 2 tablespoons.
Limit unhealthy trans fats and saturated fats. These fats, which are found in foods like butter, meat, microwave popcorn and other processed and/or fried foods, can lead to high cholesterol and heart disease, according to Harvard Health Publishing.
Carbohydrates are often thought to be the enemy when it comes to high blood sugar. But consuming the proper carbs as an evening snack can actually be beneficial, especially for people managing the Somogyi effect, per the Cleveland Clinic.
Complex carbs, which are found in foods like whole-wheat bread, whole-grain crackers and brown rice, are rich in dietary fiber, making them good choices for blood sugar control, according to the Harvard T.H. Chan School of Public Health. (Like fat and protein, fiber slows the body's ability to metabolize food into glucose, which helps keep blood sugars stable.)
Avoid quickly absorbed "simple" carbs like those found in cookies, cakes, white breads, pastas, sweetened soft drinks and juices. These carbs can cause blood sugar levels to spike and are the main culprits of high blood sugar. (Plus, they have little to no nutritional value.)
Evening Snack Ideas
The best food choices for preventing high blood sugar at night and the next morning are small, high-protein snacks that contain both healthy fats and complex carbs. You can also add in some non-starchy vegetables, according to the American Diabetes Association. These veggies — which include carrots, cucumbers, tomatoes and snap peas — are a great way to get more fiber into your diet. Not only does fiber help slow the release of glucose, it also promotes a feeling of fullness (which can keep you from overeating and therefore consuming too many calories).
Healthy bedtime snacks include:
- Plain low-fat yogurt with a handful of nuts and fresh berries
- Whole-grain crackers with tuna fish and a bit of olive oil
- A piece of whole-wheat toast with avocado and tomato
- Hummus and non-starchy vegetables like carrots, tomatoes and broccoli
If you have high morning blood sugar levels on a regular basis, be sure to discuss it with your doctor. You may need to adjust or modify your diabetes medications.
Is This an Emergency?
- National Institute on Aging: "Important Nutrients to Know: Proteins, Carbohydrates, and Fats"
- Cleveland Clinic: "Blood Sugar: Hidden Causes of High Blood Sugar Levels in the Morning"
- Harvard Health Publishing: "The Truth About Fats: The Good, the Bad, and the In-Between"
- ADA: "Non-Starchy Vegetables"
- Kaiser Permanente: "How Our Bodies Turn Food Into Energy"
- Diabetes Care: "Impact of Fat, Protein, and Glycemic Index on Postprandial Glucose Control in Type 1 Diabetes"
- Harvard T.H.Chan School of Public Health: "Carbohydrates and Blood Sugar"