EXERCISE FOR DIABETES

”More than 750,000 people in the UK have diabetes, of whom over 80% are non-insulin dependent”

Patients may also experience other symptoms or signs which indicate cardiac stress, such as dizziness, light- headedness, palpitations, and an irregular or rapid heartbeat. It’s important to slowly increase training intensity and monitor the response carefully in these circumstances.

Exercise tests using electrocardiograms (ECGs) are highly recommended before offering exercise recommendations to diabetics in order to try and diagnose silent ischamia. However the cost of the test and the relatively low detection rate of problems means exercise-ECGs are rarely carried out in diabetics.

Despite the need for caution in some cases, it is important to remember that exercise carried out at the right intensity and frequency reduces cardiovascular risk.

2Peripheral vascular disease (PVD)

In atherosclerosis the disease is usually widespread and will affect most of the larger blood vessels. Intermittent claudication (cramping pain particularly in the calf) may be a feature but blockages in the small peripheral vessels are also a major concern for exercising diabetics. The skin of diabetics is vulnerable to pressure and may break down into ulcers which often heal poorly.

Diabetes is one of the most common causes of amputation for non-traumatic medical reasons and appropriate footwear and footcare is imperative for the diabetic exerciser. For this reason activities which minimise load-bearing, such as swimming and static cycling, may be more appropriate.

3Peripheral neuropathy

The nerve impairment caused by diabetes and the resulting sensation loss may mean the patient is unable to feel the warning symptoms of pain and ulceration may occur unnoticed. If this is combined with PVD, the potential complications are greater.

4 Autonomic neuropathy

These patients tend to have a decreased activity capability because their resting heart rate is increased while their maximal heart rate is decreased. As a result, they are easily fatigued at low work intensities and are prone to hypotension after exercise. The inability to tolerate sudden changes in body position without feeling faint may indicate autonomic neuropathy which is more common in type 1 diabetes. These patients should exercise with caution and are more likely to have ‘silent’ ischaemia.

5 Retinopathy

Visual impairments resulting from background retinopathy should not be a barrier to physical activity. However, in proliferative retinopathy vessels may rupture and cause retinal haemorrhage under certain conditions. Therefore any strenuous, vigorous activity or high resistance exercises that may increase systolic blood should be avoided and light to moderate intensity exercise only encouraged.

6 Nephropathy

High intensity exercises can potentially worsen renal microangiopathy and increase albuminuria. However mild to moderate intensities of exercise can be beneficial in renal disease as well as helping to lower blood pressure. In diabetic patients on dialysis, moderate intensity exercise has improved lipid profiles and glucose tolerance.

Management of NIDDM

There are two main aims in treating diabetes: relief of symptoms and prevention of long term diabetic complications. The latter involves a long-term educational and support programme.

In most people a healthy diet and exercise, with or without blood glucose-

lowering agents, can effectively treat this type of diabetes. Poor glycaemic control is primarily corrected with diet and, in the obese patients, with weight reduction.

Oral hypoglycamic

agents If diet fails to achieve good glycaemic control pharmaceutical agents may be added. Exercise is used as an adjunct to these therapeutic measures. About 25- 30% of NIDDM patients may eventually require insulin although exercise can both postpone and reduce this risk.

Patients taking sulphonylureas which reduce blood glucose levels should be warned to watch for the signs of hypoglycaemia (see next page). They should be told to eat extra carbohydrate before exercise and to carry with them simple carbohydrate snacks at all times but particularly during exercise.

Patients taking biguanides such as metformin do not need to worry as the drug does not increase insulin production and therefore doesn’t cause hypoglycaemia. This is the drug of choice in overweight patients.

Monitoring

Urine paper strip tests which indicate blood glucose levels are adequate for NIDDM patients with mild diet-only controlled disease. However blood tests using similar testing strips are quicker and more accurate and are useful to monitor the effects of a bout of exercise on diabetic control. However a more appropriate measure is that of glycated haemoglobin (HbA1c).

Glycated haemoglobin normally constitutes about 5% of the haemoglobin in a red blood cell and is the substance to which glucose is chemically bound. In diabetics the amount of HbA1c increases proportionately to blood glucose level and therefore reflects the degree of control over a longer period (about three months). Improvements in the range of 20% have been seen in HbA1c levels with 10 weeks of aerobic training.

SportEX 11