Physical activity

Physical activity is one of the cornerstones of diabetes management. Regular physical activity of any kind can have a favourable impact on glycaemic management, cardiovascular disease (CVD) risk and overall mortality.³ However, more structured, specialised and individualised exercise prescription can achieve superior benefits.⁴ 

The goal is for people with diabetes, impaired fasting glucose or impaired glucose tolerance to accumulate at least 150 min/week of moderate- to vigorous-intensity activity with no more than two consecutive days without activity. This weekly total should include at least two moderate-to-vigorous resistance training sessions for a total of at least 60 minutes. These exercise amounts will establish and maintain muscular fitness and aerobic capacity.⁵ 

It is recommended to refer people with type 2 diabetes to an accredited exercise physiologist for the prescription of a safe and effective and sustainable exercise intervention. 

Aerobic exercise 

In people with type 2 diabetes, aerobic exercise (eg walking, cycling, swimming) reduces HbA1c, triglycerides, blood pressure and insulin resistance.⁴ 

Aerobic exercise intensity can be set as a percentage of estimated maximum heart rate (HRmax) using the equation 208–0.7×age (in years).^6,7 For moderate- and vigorous-intensity aerobic exercise, values of 55–69% and 70–89% of HRmax, respectively, can be used.⁵ 

Alternatively, ‘moderate’- and ‘vigorous’-intensity aerobic exercise are defined on rate of perceived exertion (RPE) scales as ‘somewhat hard’ and ‘hard’, respectively. Using the talk/sing test, if a person can comfortably talk but cannot sing, they are doing moderate-intensity exercise; if they are unable to talk comfortably, they are doing vigorous-intensity exercise. 

Resistance exercise 

Resistance, or strength, training involves activity such as using free weights, resistance machines or body weight. ‘Moderate-to-vigorous’ resistance training can be defined as two to four sets of 8–10 repetitions of 8–10 exercises, with rest intervals of one to two minutes.⁵ 

Resistance training reduces HbA1c.⁸ However, combining aerobic and resistance training appears to be superior compared with either alone.⁹ Both types of activity reduce CVD markers similarly,⁸ and a single bout of either may have a similar acute effect.¹⁰ 

When advising people about physical activity, general practitioners (GPs) should: 

• emphasise that some physical activity is better than none⁴ 
• discuss the importance of reducing sedentary behaviour – advise people to interrupt prolonged sitting every 30 minutes for blood glucose benefits 
• explore the risks and benefits of different forms of physical activity for the individual, taking into account whether the person is already physically active 
• explain the importance of varying the intensity of exercise levels 
• explain the importance of following the chest pain/discomfort and/or diabetes symptom management plan¹¹ 
• comment on foot care and appropriate footwear when exercising. 

Pre-exercise health assessment 

Asymptomatic sedentary people with diabetes who wish to undertake low- to moderate-intensity activity should have a CVD assessment as part of usual diabetes care; however, those identified as having CVD risk on screening tools, or who have existing atherosclerotic or functional CVD, may require more specific physical assessment prior to engaging in moderate- to high-intensity exercise. When prescribing intensity, consider that vigorous intensity exercise is more time efficient and may also result in greater benefits in appropriate individuals with consideration of complications and contraindications. The existence of diabetes complications may require specific advice (see below). 

When prescribing a physical activity program, the GP should take a careful history and be aware of the following: 

• Special attention needs to be paid to exertion-induced symptoms, chest or abdominal discomfort, claudication or syncope. 
• People with type 2 diabetes frequently have silent macrovascular disease. 
• For people with hypertrophic obstructive cardiomyopathy, heavy weightlifting and high-intensity aerobic exercise are not recommended.¹² 
• For people with long QT syndrome, exercise may trigger a cardiac arrhythmic event.¹² 
• Vigorous exercise is contraindicated for those with proliferative retinopathy, and for three months after laser retinal treatment.¹²  
• Exercise may be relatively contraindicated in people with peripheral neuropathy, a history of recurrent falls or uncontrolled hypertension.¹² 
• A foot assessment should be conducted and people advised about the importance of appropriate footwear during exercise. 
• Referral to an accredited exercise physiologist is recommended. Relevant Medicare Benefit Schedule item numbers are available. 

Any symptoms suggestive of CVD need to be actively investigated. 

Safety advice during and after exercising 

People with diabetes should be advised to moderate or cease their activity if they develop cardiovascular symptoms or feel unwell. 

People with claudication need to be encouraged to continue physical activity under appropriate clinical supervision. 

Managing blood glucose levels 

People with diabetes need to be aware of the potential delayed effects of physical activity on blood glucose levels, in particular delayed hypoglycaemia, particularly for people using insulin or sulfonylureas (or combinations of these). Postexercise hypoglycaemia can occur 12–15 hours after exercise, but is still a risk up to 48 hours after the cessation of activity.⁴ 

Advise people on how to recognise, prevent or manage glycaemic events (Box 1). Clinical advice should be given to all people to guide physical activity if they experience symptoms of a glycaemic event, including how to manage the glycaemic event, when to discontinue and continue further physical activity and when to be reviewed by their GP or other suitably trained health professional. 

Other exercise safety advice 

• Advise people to wear correct supportive footwear, especially if there is neuropathy, vascular disease, abnormal foot structure or previous foot ulcer/s, in which case the advice of a podiatrist with an interest in high-risk feet should be sought. This advice would also include the appropriateness of ‘jolting’ exercises, such as running, skipping and jumping. 
• Advise people with neuropathy or peripheral arterial disease to check their feet daily and after physical activity for blisters, warm areas or redness. 
• Advise people to stay hydrated during exercise, particularly in warmer weather.