concentration should lead to the postponement
of exercise for the reasons given above. The dose
of insulin administered before any exercise
should be scaled down to reflect the degree of
intensity and duration of exercise. However,
individual IDDM subjects may have to reach the
optimum pre-exercise insulin dose by monitor-
ing post-exercise glucose levels.
Non-insulin-dependent
diabetes mellitus
NIDDM is a world health problem and the
disease is often regarded as a disease of abnor-
mal lifestyle. About 90% of all diabetics are
NIDDM and the disease develops gradually and
is normally associated with obesity and hyper-
tension. Initially, the skeletal muscles and liver
becomes insulin resistant, but the body responds
by producing more insulin and glucose con-
centration remains normal. However, as the
insulin resistance increases, the pancreas
becomes unable to produce enough insulin to
regulate the metabolism of blood glucose con-
centration and hyperglycaemia occurs.
The pharmacological treatment of NIDDM is
poor. As the muscles are insulin resistant, insulin
therapy is not a satisfactory treatment of the
disease. There are some other drugs prescribed,
such as sulphonylureas and metformin. NIDDM
is in most case initially treated with dietary
manipulation and exercise. This treatment is
sufficient for many people with NIDDM if the
disease has not progressed too far. Exercise of
moderate intensity in people with NIDDM is
usually associated with a decrease in blood
glucose towards the normal range. A further
benefit of regular exercise is that it increases the
sensitivity of skeletal muscle to insulin, which
will have the beneficial effect of lowering the
requirement for circulating insulin concentra-
tion. It is important to recognize that exercise also
lowers the risk factors for cardiovascular disease
in people with NIDDM.
Exercise training for NIDDM
NIDDM is normally associated with obesity and
a low exercise capacity. NIDDM develops later in
life than IDDM and the majority of patients are
over 50 years old. The aims of exercise training
for people with NIDDM are therefore often dif-
ferent from those of young people with IDDM.
People with NIDDM are often untrained and an
improved level of physical fitness is normally the
main goal. As for untrained people in general,
there are large opportunities for improvement
and training studies have shown that endurance
training increases maximum oxygen uptake and
oxidative capacity in skeletal muscle (Wallberg-
Henriksson 1992).
Obesity may hinder training and a high body
mass increases the risk of injury to joints and
tendons. In people with NIDDM, it is also impor-
tant to be aware of the risk for foot problems, par-
ticularly in diabetics with peripheral neuropathy,
the diabetic athlete 463
Exercise Recovery
02 4 6 8 10 12
(mmol
.kg
–1
wet wt)
Muscle glycogen content
80
60
40
20
0
Time (h)
Fig. 34.3Glycogen synthesis in
IDDM subjects after exercise in the
presence () or absence () of
insulin. Subjects exercised at 75% of
V
.
o2max.until exhaustion and
received a carbohydrate-rich diet
and their normal insulin injection in
the control experiment. On the
other experimental day, insulin was
not injected. Adapted from
Mæhlumet al.(1978).