We're all told that exercise is great for our health, and as people with diabetes, it's even more important to incorporate an exercise routine into our daily lives. But what exercise does to our blood sugar is a whole different matter. Here, we'll sort out the mush and explain exactly how exercise impacts blood sugar, and what to do to prepare! Just a reminder to always consult your doctor before starting a new exercise routine (I am not a doctor).

What Happens to Our Blood Sugar When We Exercise?

When you exercise, especially during cardiovascular exercise (cardio), your body uses glucose as energy, whether or not you have an adequate amount of insulin in your body. If you do have insulin on board (IOB), then you're likely to experience hypoglycemia and will need to treat with fast-acting sugar. Remember to always check your blood sugar before and after exercise (it’s even better to wear a continuous glucose monitor during exercise).

During cardio, the body used two sources of fuel: sugar and free fatty acids to generate energy. Sugar energy is released from the blood, liver, and muscles. During the first 15 minutes of exercise, sugar is released mostly from the blood (your blood sugar) and muscles, with fuel (glycogen) eventually being released from the liver. After about 30 minutes, energy is released from fat stores (free fatty acids). This is how exercise depletes sugar and glycogen stores, often resulting in a lag effect of low blood sugar. Physical activity can lower your blood sugar up to 24 hours after you work out, by making your body more sensitive to insulin, so be wary of post-workout lows.

A good way to prevent lows during and after exercise is to make sure your blood sugar is sufficiently level before you start and to have snack with some fat and protein before working out. It's also helpful to not exercise when your insulin is peaking (if you just ate breakfast and have dosed a meal bolus within the past 90 or so minutes). What some people with diabetes recommend is eating a low or no carbohydrate meal before exercising (as opposed to a moderate or high carb meal), so you have less insulin on board. There's less room for error, and the less active insulin you have in your body, the less likely you are to go low during exercise.

If your exercise routine is longer than several hours, reducing basal insulin post-exercise, and eating plenty of high fat and high protein foods can stave off lows for the next 24 hours.

Why Do Some People Suffer from Hyperglycemia When they Exercise?

Some people experience hyperglycemia as a result of exercise, and while this phenomenon is rarer, it does still happen. So, what gives? High blood sugar usually occurs during weightlifting or strength training. Weightlifting has been known to provoke the adrenal glands of the body, initiating the flight or fight response, which releases certain hormones and glucose in the bloodstream that can make your blood sugar skyrocket. Certain competitive events, such as races, also cause the body to release adrenaline, which has adverse effects on blood sugar, too.

When you're doing anaerobic activities, with short bursts of energy (during weightlifting, for example), the body releases huge amounts of adrenaline. That adrenaline signals your liver to release large amounts of sugar into your bloodstream, resulting in high blood glucose levels. In people without diabetes, their blood sugars fall naturally after a few hours, but insulin-dependent diabetics may sometimes require a post-workout insulin dose.

A good way to help prevent hyperglycemia during strength training and weightlifting exercises is to use a temporarily increased basal program during the duration of your workout and to avoid a high carbohydrate meal before starting. Test your blood sugar often, and do not exercise if you have or develop ketones, as this can make you very sick. You know your body best, and it's best when you listen to its cues!

Ultimately, the impact that physical activity has on your blood sugar will vary depending on the intensity of your exercise, the type of your exercise, how long you exercise, and many other factors, but one thing that we can all agree on is that exercise is great for people with diabetes. It can help you respond to insulin better, lower your risk for heart disease, help you lose weight, and will increase your confidence. Learn your body, and how exercise can best benefit you.

The importance of exercise when you have diabetes



For people who have diabetes or almost any other disease, for that matter, the benefits of exercise can't be overstated. Exercise helps control weight, lower blood pressure, lower harmful LDL cholesterol and triglycerides, raise healthy HDL cholesterol, strengthen muscles and bones, reduce anxiety, and improve your general well-being. There are added benefits for people with diabetes: exercise lowers blood glucose levels and boosts your body's sensitivity to insulin, countering insulin resistance.

Many studies underscore these and other benefits from exercise. Following are some highlights of those results:

• Exercise lowered HbA1c values by 0.7 percentage point in people of different ethnic groups with diabetes who were taking different medications and following a variety of diets and this improvement occurred even though they didn't lose any weight.
• All forms of exercise aerobic, resistance, or doing both (combined training) were equally good at lowering HbA1c values in people with diabetes.
• Resistance training and aerobic exercise both helped to lower insulin resistance in previously sedentary older adults with abdominal obesity at risk for diabetes. Combining the two types of exercise proved more beneficial than doing either one alone.
• People with diabetes who walked at least two hours a week were less likely to die of heart disease than their sedentary counter- parts, and those who exercised three to four hours a week cut their risk even more.
• Women with diabetes who spent at least four hours a week doing moderate exercise (including walking) or vigorous exercise had a 40% lower risk of developing heart disease than those who didn't exercise. These benefits persisted even after researchers adjusted for confounding factors, including BMI, smoking, and other heart disease risk factors.

In general, the best time to exercise is one to three hours after eating, when your blood sugar level is likely to be higher. If you use insulin, it's important to test your blood sugar before exercising. If the level before exercise is below 100 mg/dL, eating a piece of fruit or having a small snack will boost it and help you avoid hypoglycemia. Testing again 30 minutes later will show whether your blood sugar level is stable.

It's also a good idea to check your blood sugar after any particularly grueling workout or activity. If you're taking insulin, your risk of developing hypoglycemia may be highest six to 12 hours after exercising. Experts also caution against exercising if your blood sugar is too high (over 250), because exercise can sometimes raise blood sugar even higher.

Because of the dangers associated with diabetes, always wear a medical alert bracelet indicating that you have diabetes and whether you take insulin. Also keep hard candy or glucose tablets with you while exercising in case your blood sugar drops precipitously.