1. What are symptoms of low and high blood sugar?

Low or high blood sugar, also referred to as blood glucose, can be very dangerous. Low blood sugar causes a variety of symptoms that include sweating, feeling hungry or anxious, weakness, confusion, seizures, rapid heartbeat, nausea, blurred vision, or headaches.¹ If blood sugar levels drop too low, it can result in a coma or even death. Low blood sugar is an important signal that glucose metabolism is off-balance in individuals with certain conditions, or under severe conditions such as exercising to exhaustion or extreme fasting. For most people consuming a healthy diet, they may notice mild symptoms associated with hypoglycemia, or low blood sugar — what we often notice as feeling “hangry”.

On the other end of the spectrum is high blood sugar, or hyperglycemia. Our bodies can handle large fluctuations in blood sugar levels. If they stay high for a long time, you’ll start to notice the symptoms that include confusion, nausea, vomiting, shortness of breath, increased thirst and frequent urination.² If left untreated, high blood sugar levels can progress to ketoacidosis, which is life-threatening and requires immediate treatment. A short-term bout of hyperglycemia may result in mild increase in thirst and feeling unwell. Chronically high blood sugar levels can result in serious symptoms as well as organ damage.³

 2. What is a normal blood sugar level?

To keep your body feeling good, it is important to keep blood sugar in a normal range. But what is a normal blood sugar level? “Normal” can be difficult to define; we, as humans, differ in many aspects that affect blood sugar levels. In terms of diagnostic markers, a normal blood sugar level would measure between 70 to 99 mg/dl (3.9 to 5.5 mmol/l) under fasting conditions. Sugar should be measured in a fasted state because of the profound effect of food on blood sugar levels.

Normal blood sugar levels will occur when the blood sugar response is normal. Again, there will be some level of variation in blood sugar response, but it is typical for levels to increase after a meal as the body metabolizes, or breaks down, nutrients for use throughout the body. Blood sugar levels should peak around 90 minutes and return to where they were before you ate your meal after about two hours.⁴ If blood sugar levels skyrocket, they are likely to come crashing down — something we’d like to avoid. If blood sugar levels stay elevated for too long, you’ll probably start feeling the symptoms of hyperglycemia. This is also not normal. The body is equipped to respond to high blood sugar after a big indulgence. But long-term, the goal for healthy blood sugar levels is to keep them in a stable range to avoid peaks and valleys.

 3. How do I lower blood sugar?

The biggest step you can take to lower your blood sugar in both the short and long-term is to reduce your intake of refined carbohydrates because they cause a large spike in blood sugar levels. Choosing fiber-rich, nutrient-dense foods can help blunt the increase in blood sugar as the food is broken down.⁵ In the long-term, this type of diet also helps stabilize blood sugars and can lower HbA1c — a long-term measure of blood sugar.

But what can you do if you find yourself feeling unwell after a big, sugar-filled meal? Your body will take time to process the sugar, but one option is to take a walk to help lower blood sugar. Exercise after a meal can help shuttle sugar into cells and out of your blood.₄ It doesn’t have to be running three miles at a quick pace; a simple but moderate-paced walk around the block will produce the sugar-lowering benefits. Exercise causes glucose transporters to move to the surface of the cell in response to exercise, which allows sugar to enter the cell and reduces levels in the blood.

4. What causes fluctuations in blood sugar?

Blood sugar levels are determined by many factors, and that can make it difficult to predict how blood sugar will change. The food we eat is the biggest reason for fluctuations, as well as the timing of meals. Carbohydrate-heavy meals can cause high blood sugar, whereas balanced meals will result in a less intense peak. Similarly, fasting for too long can cause blood sugar levels to drop as the body begins to use up its storage form of carbohydrates. Other choices or conditions that can cause fluctuation in blood sugar factors include exercise (intensity, duration, and type of exercise), sleep quality and quantity, stress levels, and hormones or changes in hormones, infections, use of certain medications, and dehydration.⁶

References

1. American Diabetes Association. (https://www.diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hypoglycemia) Accessed 7/12/2022.
2. American Diabetes Association. (https://www.diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hyperglycemia) Accessed 7/12/2022.
3. Bonner, R., Albajrami, O., Hudspeth, J., Upadhyay, A. (2020). Prim Care, 47(4):645.
4. Erickson, M.L., Jenkins, N.T., McCully, K.K. (2017). Front Endocrinol, 8:228.
5. Papakonstantinou, E., Oikonomou, C., Nychas, G., Dimitriadis, G.D. (2022).. Nutrients, 14(4):823.
6. Loneman, S.M. (2022, June 7). The Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/diabetes/expert-answers/glucose-levels/faq-20424316