How to Keep Blood Sugar Numbers Down with Diet and Exercise
April 24, 2018
How to Keep Blood Sugar Numbers Down with Diet and Exercise
Family of four riding bikes

Diet and exercise is a struggle to keep up with for most of us, but if you have diabetes, you know how much harder it can be. Diet and exercise can both affect your blood sugar levels, but if you only check your blood sugar when you start feeling bad, it’s even harder to nail down what exactly caused your levels to spike or dip.

We spoke with Joyce Harrell, registered dietitian and diabetes educator at the Diabetes Wellness Center at Texas Health HEB, to understand how regularly checking your blood sugar can work with your diet and exercise plan to help you control your diabetes better and stay ahead of any spikes or dips before they happen.

When you eat, your food is broken down into a sugar called glucose. Glucose gives your body the energy it needs to work, but in order for your body to use glucose, it needs help from insulin. When you have diabetes, your body does not make enough insulin or use it efficiently, which causes the glucose to stay in your blood.

Your blood glucose, or blood sugar, level is an essential measure of your health, but when you have diabetes, regularly checking your blood sugar is a crucial part of controlling the disease since your body cannot naturally regulate your blood glucose level.

“Checking your blood sugar is giving you immediate feedback about how your body is responding to different things,” Harrell says. “When you eat a meal, exercise, feel stressed, are drinking less water, or other things occur, your testing tells you how this affects you. Just testing when you feel bad is like a very small bandage for your diabetes control.” The new Continuous Glucose Monitoring Systems available are very useful to identify blood glucose trends which help patients make better decisions for meals and care during exercise.

How often you should test your blood sugar varies from person to person and is something your doctor will discuss with you, but Harrell says you should be checking your blood sugar at least once a day.

“The bottom line: find out how things are working for you,” Harrell says. “If you need to test two to three times a day (or more) to discover how you are doing, then that will benefit you a great deal. Also, if you are going through some changes in your life, testing more frequently makes a lot of sense to help keep you on track.”

If you are taking insulin, Harrell says you need to check prior to every meal so you can properly administer the correct dose, something your doctor will work with you to learn how to do.

Checking your blood sugar often can help you make decisions about food and activity throughout the day, but it can sometimes be hard to understand what can raise your blood sugar levels and what can cause them to dip too low.

According to the American Diabetes Association, common causes for blood sugar spikes include:

  • Eating too much food, especially if it is high in carbohydrates
  • Improper dosage of insulin or medication, or skipping medications
  • Not getting enough exercise
  • Drug interactions
  • Illness — Hormones released by your immune system to fight your illness raise blood sugar levels
  • Stress ? Hormones produced when we are stressed raise blood sugar levels
  • Short- or long-term pain, like that caused by a sunburn or pulled muscle
  • Menstrual periods, which cause changes in hormone levels
  • Dehydration

Common causes for blood sugar dips include:

  • Not enough food, like a meal or snack with fewer carbohydrates than usual, missing a meal or snack
  • Too much insulin or oral diabetes medications
  • Side effects from other medications
  • More physical activity or exercise than usual

Exercise plays a very important role in controlling diabetes as well as improving your overall health, so you may be scratching your head as to how too much of it could be bad for your blood sugar levels. Harrell explains that physical activity makes your body more sensitive to insulin and can lower blood glucose, so too much exercise all at one time, or more than you’re used to, can cause your blood glucose to fall dangerously low.

“Exercise helps to lower your blood glucose for the next 24 hours, so daily exercise is really important,” Harrell says. “But safety is also important, and being in a safe range with your blood glucose prior to exercise helps (prevent issues).”

If your blood glucose is between 135 and 240, then Harrell says you are in a safe range, in which moderate exercise won’t cause your blood sugar to drop sharply during your workout. But she cautions that if your blood glucose is below 135, you should eat a snack, ideally a carbohydrate with a protein and a fat, before exercising, and if your blood sugar is about 240, you should try to bring it down to a safe range with water or wait until later in the day.

Harrell provides the scenarios below as examples of how to control your blood sugar before and after working out:

Scenario 1: Your blood glucose is 120 prior to your trip to the gym. During the next hour, you spend 20 minutes on the treadmill, 20 minutes on different weight machines (weight training) and then 20 minutes on the elliptical or doing yoga.

You are burning quite a few calories with all of this, which is also burning carbohydrates or stores of glycogen, so during the last 10 minutes of exercise you begin feeling weak and notice blurred vision.

You check your blood glucose and it is now 65. If you had not stopped to check your blood sugar levels and respond, you would have been at risk of passing out, which can lead to a diabetic coma unless treated quickly. This is a hypoglycemic event, and you should have glucose tablets with you to correct this quickly, and a snack to have after you have corrected your blood glucose.

Scenario 2: Your blood glucose is 268 prior to exercise and you do the same exercise noted in Scenario 1.

You finish your exercise and go home. An hour later you check your blood glucose and it is now 341. You check every hour and note it is still rising. This prompts you to take action by drinking a lot of water to help bring your blood glucose levels down and calling your doctor.

Whether you’ve had diabetes for a long time or you have been recently diagnosed, it’s important to remember that diabetes is highly manageable, and with the guidance of your medical team, there’s a lot that you can do to keep yourself healthy! Making a commitment to regularly test your blood sugar can help you on your journey of staying happy and healthy while living with diabetes.

For more information about diabetes, Texas Health’s diabetes outpatient centers and to take a diabetes risk assessment visit

We use cookies and similar technologies to enhance your experience on our website and help us
understand how our site is used as described in our Privacy Statement and Terms of Use. By
using this website, you are agreeing to our Terms of Use.
Accept and Close