Diabetes can affect how your body reacts to exercise—a trainer explains how to adapt your workouts to manage blood sugar levels and work out safely

Not knowing what to lift or how hard to push yourself during a workout is a common issue for those new to exercise.

But it’s all the more daunting for the 40 million or so Americans living with diabetes.

People with this chronic condition—representing around 12% of the US population according to the CDC—can find their blood sugar levels are too high because their body is unable to produce enough insulin or can’t use it effectively.

While exercise can improve insulin sensitivity, promote glucose metabolism and maintain blood sugar levels at a healthy level, too strenuous a workout could trigger glucose levels to rise or drop rapidly, leading to potentially dangerous side effects.

Despite these implications, certified strength and conditioning specialist Garett Reid of the BetterMe app says there is “no inherent reason” why someone living with the condition can’t train exactly the same as anyone else.

“You just need to take adequate precautions and learn how your body responds to exercise over time,” he says.

Reid was speaking to Fit&Well as BetterMe has recently launched a series of workouts for people with diabetes in collaboration with charity Diabetes UK.

Here, the NSCA-certified trainer outlines three ways people living with type 1 or type 2 diabetes can get started with exercise or modify their usual routine to train safely.

Three ways you should exercise differently with diabetes

Before outlining how people with diabetes should modify their approach to exercise, Reid says it’s imperative to remember that this condition can affect everyone differently.

“One thing that should be very clear is that everything we say is a guideline,” he says.

“Diabetes is a very personalized condition, whether you have type 1 or type 2, or how far along you are, so everything should be very personalized.”

But the general gist is to “approach training to see how your body adapts and that generally means lower intensity and shorter sessions.”

1. Take it slow for the first month after your diagnosis

Long-term, Reid says people with diabetes “do not intrinsically have to train differently down the road” so long as they take it slow when getting back into exercise.

Reid tells his clients to take it slow and exercise caution, especially in the first month.

“You should be a little bit more careful with everything,” he says.

“Your sessions should be a little bit shorter. A little bit less intensity. A little bit less volume. And your main focus should be on testing your blood sugars.”

An optimal session would be no more than half an hour with plenty of rest between exercises.

“Keep sessions short—no more than 30 minutes. Longer workouts of 60 or 90 minutes have more of a dramatic effect on glucose levels,” he says.

2. Test before, test after and test later

Not everyone will need to regularly test their blood sugars. For example, some people with type 2 diabetes will not be on glucose-lowering medication.

But if you've been told you need to, regularly monitoring your blood sugar levels 30 minutes before, immediately after exercise and two-to-four hours later will help build a picture of how your body responds to exercise, Reid continues.

• 30 minutes before: to determine if your levels are safe
• Immediately after: to monitor the immediate effect of the workout
• Two-to-four hours later: to see how your levels have settled

BetterMe’s plan incorporates regular reminders via voice prompts during its workouts to check blood sugar levels so users can adjust intensity or take action if needed.

Tracking these fluctuations and writing down your results will allow you to recognize trends in how your body responds to exercise.

Over time, the accumulation of this knowledge is what allows you to increase your training intensity and duration.

“Resistance training can cause a spike in blood sugar levels when glucose is released into the bloodstream,” explains Reid.

Whereas “prolonged cardio is more likely to decrease glucose levels.”

Testing two-to-four hours after finishing your workout helps you avoid “making brash decisions,” he says, meaning you’ll know if your levels have returned to normal naturally or if you need to start making adjustments with insulin or dietary choices.

You may also need to continue to check them for up to 24 hours after exercise, as your body may be more sensitive to insulin, increasing your risk of delayed hypoglycemia.

“Dangerously low blood sugar is an exception,” notes Reid.

“If your blood glucose falls too low during or immediately after exercise, stop exercising, consume 15–20g of fast-acting carbohydrates, wait about 15 minutes, then recheck your blood glucose. Only resume exercise once your levels have recovered and you feel well.”

3. Prioritize strength training—but don't neglect cardio

Both strength training and cardio workouts can improve insulin sensitivity and glucose metabolism.

However, strength training is generally regarded as especially beneficial for people with diabetes because it helps increase lean muscle mass which can aid glycogen storage.

“About 80-85% of glycogen, the stored form of glucose, is stored within your muscles,” says Reid. “So having more muscle mass means you don't have as much glucose running through your blood.”

That said, cardio training, including walking, running, cycling and swimming, can improve muscle function, helping make that muscle “work even better and be even more sensitive to insulin.”

Reid says a good beginner plan for someone with diabetes should be built around a full-body strength workout, repeated two to three times per week, focusing on using one compound movement per body part.

For example, a squat for the legs, chest press for the chest, bent-over row for the back and shoulder press for the shoulders.

“Generally, you can use free weights or machines,” he says.

“Start off with two sets per exercise, eight to 12 reps per set, and stop three to four reps before failure to keep intensity low,” he says.

Take it slow, see how your blood sugar levels react, and build gradually from there as you start to learn how your body responds to exercise.

How to progress safely over time

As you become accustomed to each workout and learn how your body responds, Reid says you can start to cautiously increase the duration and intensity of these sessions.

However, you should adopt the same precautions outlined above whenever you try a new form of training.

“If you only strength trained for a few months, then planned to add prolonged steady-state cardio, follow the same precautions because your body might respond differently,” he says.

“Ideally your body's [response to exercise] will have improved but it's still good to note and be mindful of how it reacts to a different stimulus.

“You may have adapted to strength training but you'll still need to monitor how your body reacts to cardio.”

Ultimately, the benefits of exercise for people with diabetes far outweigh the risks, but it’s always best to consult a healthcare professional first to fully understand what is suitable for your individual needs.