Introduction
Diabetes mellitus is a disease of abnormal regula-
tion of glucose metabolism, resulting in an
elevated blood glucose concentration which
may arise for different reasons. Consequently,
the treatments of the disease are varied. Exercise
training for people with diabetes mellitus must
also be viewed in the light of the aetiology of the
disease, as the physiological response to exercise
can differ. In one form of diabetes mellitus, train-
ing is regarded as a cornerstone in the treatment
of the disease, whereas training is a challenge in
the other form of diabetes.
Diabetes mellitus is classified into two distinct
types:
1 Insulin-dependent diabetes mellitus (IDDM,
or type I or juvenile diabetes), which requires
insulin replacement on a daily basis because
insulin secretion is almost totally lacking.
2 Non-insulin-dependent diabetes mellitus
(NIDDM, or type II), in which the early
pathological lesion is a decreased sensitivity of
skeletal muscle and liver to insulin (insulin resis-
tance). The initial period of insulin resistance is
associated with increased circulating concentra-
tions of insulin, but the blood glucose concentra-
tion remains normal. NIDDM develops when the
pancreatic b-cell is no longer able to secrete the
appropriate amount of insulin to maintain ad-
equate blood glucose concentrations and hyper-
glycaemia is the direct consequence.
The incidence of diabetes mellitus has in-
creased during recent decades. In particular, the
incidence of NIDDM has increased dramatically
and up to 10–20% of people over 65 years old
suffer from NIDDM in many countries. NIDDM
is associated with an increased risk for many dis-
eases such as coronary heart disease, neuropathy,
renal failure, and blindness (Kahn 1998). In
NIDDM, the management of blood glucose con-
centration with prescribed pharmaceutical drugs
is poor and diet and regular physical exercise are
important therapeutic treatments for the disease.
Only a small portion of diabetics (about 10%)
are IDDM, but this group requires particularly
close monitoring because IDDM develops early
in life. Exercise training and physical activity
are natural things for children to do and the
opportunity to participate in sports is important
for social development. IDDM is treated with
insulin and the combination of exercise training
and insulin injection may cause too high a stimu-
lation of peripheral glucose uptake, resulting in
hypoglycaemia. The requirement of insulin is
influenced by exercise and the dose of insulin
must therefore be varied with the intensity and
duration of exercise. Thus, in people with IDDM
physical exercise must be regarded as a chal-
lenge, but, with education and management,
people with IDDM can participate in exercise
training together with non-diabetics, and can
achieve the same health benefits.Regulation of carbohydrate and
fat metabolism during exercise
In working skeletal muscle, the demand for for-