Blood Sugar: Here’s How to Measure It and Tell if Your Level Is Healthy

High blood sugar levels are a problem, even if you don’t have a family history of diabetes. Blood sugar that’s consistently higher than ideal can coexist with Type 2 diabetes and cause serious health conditions like kidney disease, nerve problems or stroke.

While that’s no reason to panic, when it comes to our health, it’s important to know exactly what’s going on inside of our bodies. Let’s get into what blood sugar means, how to measure it and everything else you need to know.

What is blood sugar?

Blood sugar, or glucose, is your body’s main energy source.

We get glucose from the food we eat, and our blood carries it around to all the cells in the body to give them energy to function. Glucose mainly comes from the carbohydrates we eat, though our bodies can convert protein and fat into sugar too if needed. Glucose from protein is typically stored in the liver and doesn’t enter the bloodstream, so eating protein-rich foods won’t raise your blood sugar too much. Fats slow down the digestion of carbohydrates, which causes a delayed rise in blood sugar. High blood sugar can be an issue because it usually leads to sugar crashes, which are no fun — symptoms include fatigue, headaches and the jitters.

So, eat meals balanced with protein, fat and carbs to avoid this. Read more: How Sugar Can Temporarily Sabotage Your Immune System Blood sugar is closely related to insulin, a hormone secreted by the pancreas that helps your body use glucose that’s in the carbohydrates you eat.

Insulin helps regulate your blood sugar levels — if you eat more sugar than you need in the moment, the hormone helps store the glucose in your liver until it’s needed for energy. You probably also know about blood sugar in the context of diabetes. Type 1 diabetes is a condition in which people are unable to make insulin, so they need to inject the hormone in order to keep their blood sugar levels stable. People with Type 2 diabetes, which usually occurs later in life, either don’t secrete insulin or are resistant to it.

How do I measure blood sugar?

If you have diabetes, you probably already keep a watchful eye on your blood sugar through the use of a continuous glucose monitor (a CGM) or a blood sugar meter (which involves pricking your fingertip). Blood sugar measurement is also typically included in routine lab work for people without diabetes — your physician will usually order a glycated hemoglobin (A1C) test, which measures your average blood sugar over the past two to three months.

Say your A1C test comes back with no sign of diabetes — constantly measuring your blood sugar can still be helpful. For instance, some people experiment with using a CGM to see how their body responds to different types of food. However, it’s good to note that this is a fairly cost-intensive way of figuring out your nutrition, and writing down a food diary that includes how you felt after each meal will also help you figure out what to eat.

Check out these blood sugar monitors if you’re looking for recommendations on how to keep track of your levels at home.

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What should my blood sugar levels be?

Your blood sugar level changes depending on what you’ve eaten, whether you’ve exercised and other factors (more on that later) but we have some general guidelines to determine what levels are healthy. For generally healthy individuals (without diabetes) who haven’t eaten for 8 hours or more, a normal blood sugar level is between 70-99 mg/dL. When you’ve eaten in the past 2 hours, it should be no higher than 140 mg/dL.

To refresh your chemistry knowledge, that unit is milligrams per deciliter (one tenth of a liter) and it’s measuring the amount of glucose present in your blood. Only a medical professional can diagnose diabetes or another issue with your blood sugar, so if you’re concerned about your blood sugar levels, check with a doctor.

How can I tell if my blood sugar is irregular?

Again, only a doctor can diagnose a problem with your blood sugar. But you may be wondering how to know if it’s something you should get checked out.

There can be two main issues with your blood sugar — either it’s consistently too high or too low. Even if you don’t have diabetes, there are some signs that your blood sugar levels are not functioning normally. Hypoglycemia is a condition in which your blood sugar is too low.

Signs include an irregular heartbeat, fatigue, shakiness and tingling or numbness in your face. If you consistently feel this way when you get hungry or between meals, talk to your health care provider. On the flip side, hyperglycemia happens when your blood sugar is too high, and can happen to nondiabetics. Symptoms include frequent urination, increased thirst and headache.

If you think you’re hyperglycemic and can’t keep fluids or food down, call for emergency medical assistance.

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What factors affect blood sugar?

You can guess that carbohydrate intake and insulin production are at least partly responsible for your blood sugar levels. But the list is much longer — almost every lifestyle choice you make can affect your blood sugar. Here’s just a partial list.

Exercise can affect insulin sensitivity, leading to lower blood sugar for up to 48 hours.
Alcohol intake increases insulin production, causing low blood sugar.
Stress hormones like cortisol can raise blood sugar, because your body wants access to energy in order to escape what it perceives as a dangerous situation.
Medications, especially statins and diuretics, can raise blood sugar.

Statins are used to treat cholesterol, and diuretics for high blood pressure.
Diet is a major player in blood sugar.

Eating too many simple carbs at once can cause levels to skyrocket, while protein intake leads to a slower increase in blood sugar.
Dehydration raises blood sugar, because with less water in your body the glucose concentration will be higher.

Other surprising factors can affect your blood sugar, like a sunburn or gum disease, so if you’re dealing with a blood sugar issue and can’t figure out what’s causing your spikes and dips, talk to a healthcare professional.