How can I monitor my blood glucose if I am an athlete with diabetes?

If you are an athlete with diabetes you can monitor your blood glucose with a continuous glucose monitor (CGM). A CGM can give you hundreds of readings every day without having to prick your finger, and it can tell you if your blood sugar is rising or falling. It can allow you to be physically active and have a sense of control.
Dr. Jack Merendino, MD
Endocrinology Diabetes & Metabolism
There are plenty of professional athletes who have both type 1 and type 2 diabetes, and my own medical practice includes people with diabetes who are marathoners, endurance cyclists, basketball, tennis and soccer players, swimmers and even water polo players. So there is no reason that someone with diabetes should play or compete in athletics, whether it’s just for fun or at a high competitive level. But performing your best on the field, court, track or in the water requires that you understand what happens to your blood sugar when you are playing or competing.

Everyone knows that exercise is good for blood sugar control as well as for your general health. But that doesn’t necessarily mean that blood sugar will drop when you begin exercising or playing. The release of adrenaline and other hormones that are required for athletic performance may actually raise blood sugar in the short-term. Many people find that during competition their blood sugar actually rises as their body makes sugar available from storage to power your muscles. Many times this is followed by a fall in blood sugar levels an hour or more after the athletic performance ceases. So exercise or athletic competition is sometimes accompanied by rapid or wide fluctuations in blood sugar levels. 

It’s important to understand how your body and your blood sugar reacts to exercise or athletic competition. It is often necessary to do a lot more fingerstick blood sugar testing than usual to figure out exactly what your pattern of blood sugar fluctations is during the athletic activity. The good news is that once you figure out your pattern, it is usually more or less the same when you repeat the same activity.

My suggestion in most cases is that one someone undertakes a new exercise or athletic competition that they test at the start of the activity and frequently during the exercise -- maybe every half hour or so -- until a couple of hours afterward. This will establish a pattern. If the person finds that her blood sugar falls during exercise, then she will need to eat some healthy, carbohydrate-containing food before starting the exercise. If another person’s blood sugar first rises, but then falls fairly quickly after the exercise is over, then he will need to eat something after exercising. For someone using short-acting insulin, the dose necessary for a meal that either precedes or follows exercise may need to be adjusted downward to account for the sugar used by the exercise. 

Once someone knows his or her pattern of rises and falls with exercise or competition, it will not be necessary to check nearly as frequently, and in some cases not at all if the person feels well and generally can sense low blood sugar reactions well. But it’s important to re-do the frequent testing when ratcheting up the exercise as the pattern may be somewhat different or the rise and fall in glucose levels may be more pronounced.
Phil Southerland
Not every athlete with diabetes uses a pump. It’s a matter of personal preference. If you don’t like doing shots, and you don’t want to do more than four shots a day, I’d definitely recommend asking your doctor about an insulin pump.

There are a million ways when it comes to diabetes control. Each person needs to have what they feel is the best bag of tricks to do it properly. On the Race Across America team, we had six riders on the pump and two on Lantus. Personally, I use a combination of Lantus, Apidra (a fast-acting insulin) and the continuous glucose monitor. My co-founder, Joe Eldridge, a professional cyclist, uses the pump with Apidra and the glucose monitor. Athletes are always trying to fine tune what we do and to do it better.

Continue Learning about Diabetes


Diabetes mellitus (MEL-ih-tus), often referred to as diabetes, is characterized by high blood glucose (sugar) levels that result from the body’s inability to produce enough insulin and/or effectively utilize the insulin. Diabetes ...

is a serious, life-long condition and the sixth leading cause of death in the United States. Diabetes is a disorder of metabolism (the body's way of digesting food and converting it into energy). There are three forms of diabetes. Type 1 diabetes is an autoimmune disease that accounts for five- to 10-percent of all diagnosed cases of diabetes. Type 2 diabetes may account for 90- to 95-percent of all diagnosed cases. The third type of diabetes occurs in pregnancy and is referred to as gestational diabetes. Left untreated, gestational diabetes can cause health issues for pregnant women and their babies. People with diabetes can take preventive steps to control this disease and decrease the risk of further complications.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.