People who suffer from type 2 diabetes should not shy away from exercise, which can help to improve daily functioning and enhance the overall quality of life.
People with type 2 diabetes have high blood sugar because their cells are unable to use the hormone insulin to absorb glucose, which is needed for energy, said Dr Joan Khoo, consultant endocrinologist and director of Changi General Hospital's Diabetes Centre.
This can lead to a wide range of complications, including damage to the eyes and kidneys and the hardening of the arteries.
The American College of Sports Medicine recommends regular exercise for diabetics, said Mr Ray Loh, an exercise physiologist at the Sports Medicine and Surgery Clinic at Tan Tock Seng Hospital.
"Exercise has long been recognised as part of the treatment and management of type 2 diabetes in patients as it plays an important role in the treatment and prevention of insulin insensitivity," he said.
As muscles take up sugar from the blood to fuel their activity, regular exercise increases their need for more fuel, which in turn lowers the blood sugar level and insulin resistance, he explained.
Some studies have shown an increase in glucose sensitivity for at least 16 hours from just a single session of exercise, said Mr Loh.
Over time, fewer types of medication may be needed to control diabetes.
Exercise helps reduce the risk of diabetic complications and cardiovascular disease through weight loss and improvement in overall physical abilities, such as aerobic function, endurance and muscular strength, said Mr Loh.
Exercise can also prevent the development of type 2 diabetes for those who are at risk or are pre-diabetic - those with abnormally high blood-sugar levels that may progress to become full-blown type 2 diabetes.
What To Watch Out For
WHAT TO WATCH OUT FOR
Exercise for those with diabetes should be structured, said Mr Loh.
The timing of the exercise should take into consideration when they take their meals and diabetic medication. Exercise is not recommended during peak insulin action as it could lead to hypoglycaemia or low blood sugar, he said.
Peak insulin action would depend on each individual's diet, rate of food digestion and type of medication taken, Mr Loh said.
Some types of insulin medication are slow-acting, while others are fast-acting, and each individual reacts differently to them as well, he said.
That is why those with diabetes have to keep testing their blood sugar levels, he added.
The symptoms of low blood sugar include nervousness, cold sweat, intense hunger, weakness and heart palpitations.
This can be corrected by eating some carbohydrates, but if nothing is done to raise blood sugar levels and the levels continue to drop, the diabetic patient could develop confusion, drowsiness and changes in behaviour.
Post-exercise hypoglycaemia can also be delayed, so exercising just before going to bed is also not recommended, said Mr Loh.
If one is sleeping too soundly to wake up to eat, the hypoglycaemia could worsen and lead to disorientation, confusion and even convulsions and coma, he said.
Blood monitoring using a glucose meter before and after exercise is required for patients with type 2 diabetes to exercise safely. Before exercise, the blood sugar level should be above 5.5 millimoles per litre (mmol/L) and below 13.8mmol/L.
This helps to ensure that you are starting your exercise with a blood glucose level that is less likely to send you into a hypoglycaemic episode, especially after you go to bed, said Mr Loh.
If the blood sugar level is around 5.5mmol/L before or after exercise, eat about 20 to 30g of carbohydrates, he added.
On the other end of the spectrum, diabetics have to watch out for hyperglycaemia, or high blood sugar, as it might lead to dehydration that could compromise the body's ability to maintain its core internal temperature.
If the blood sugar levels stay higher than they should be for prolonged periods, the kidneys will attempt to remove some of the excess sugar from the blood and pass it out through the urine.
While the kidneys filter the blood in this way, water will also be removed from the blood and will need replenishing.
That is why those with this condition tend to have increased thirst when the blood sugar levels are too high, said Mr Loh.
Other symptoms include frequent thirst and urination, blurred vision, fatigue and frothy urine or sugar in the urine (ants may be seen in the toilet bowl).
Light exercises are recommended if the person is still feeling well even though his blood glucose level is more than 13mmol/L, Mr Loh said.
This is because blood sugar levels will usually decrease during exercise.
People with diabetes do not generally need to postpone exercise because of high blood glucose level, provided they are feeling well and ketones are not present in the urine, said Dr Khoo.
Ketones are produced when the body is unable to obtain glucose for fuel and burns its own fat instead.
This becomes toxic if the concentration of ketones reaches a certain level.
Dr Khoo cautioned that if the blood glucose level is more than 16.7mmol/L, it can cause ketones in the urine.
In cases where the blood glucose level is more than 24mmol/L, exercise is not recommended, said Mr Loh.
How Much Exercise?
HOW MUCH EXERCISE?
How much a person should exercise depends on his fitness level and if he has other medical problems, such as heart conditions and problems with blood circulation in the legs.
Diabetic patients should check with their doctors before embarking on a regular exercise programme.
For most patients, at least 150 minutes a week of moderate aerobic exercise, such as brisk walking, cycling and swimming, is recommended, said Dr Khoo.
This should be spread between at least three days in a week, with no more than two consecutive days between exercise sessions, she added.
Most patients do not need to avoid specific exercises, but those with reduced sensation or ulcers in the feet should avoid high-impact exercises, such as jogging and high-intensity aerobics, she said.
Strength training with small weights or resistance bands, and flexibility or balance exercises under supervision, are also useful, she added.
The next article will discuss in detail the exercises recommended for those with type 2 diabetes.
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