Diabetes mellitus and the Nijmegen 4-day marches: the sweet effects of walking exercise

Type 2 diabetes mellitus (T2DM) represents a major health problem in the
Western society. Physical inactivity plays a detrimental role in the
development of T2DM, but also contributes to the increased cardiovascular risk.
To support this notion, exercise training has various beneficial effects,
including improvement in insulin sensitivity and cardiovascular risk factors.
Walking exercise represents an attractive type of exercise that can be
performed everywhere. Moreover, participating in a training program in
preparation for a walking event (i.e. Nijmegen 4-Day marches) may enhance
motivation to perform exercise and remain physically active after cessation of
the training program. Since relatively little is known about the effect of
walking exercise training on insulin resistance and cardiovascular risk
factors, the current study will be conducted.
When walking exercise is performed for prolonged periods, such as during the
Nijmegen 4-Day marches, subjects may develop fluid- and electrolyte imbalance.
We found that such problems occur more often in men, older subjects and
overweight/obesity. Whether patients with T2DM are prone to develop such
problems during prolonged walking is not known. Moreover, relatively little is
known about the impact of prolonged walking exercise on glucose levels, which
may be importantly influenced by prolonged walking exercise.

The first objective is to examine the impact of 4-month walking training on
physical fitness, insulin resistance and cardiovascular risks in T2DM and their
controls and to assess whether these effects are preserved 3 months after
cessation of the training program. The second aim is to assess the impact of
prolonged walking on fluid- and electrolyte balance and glucose homeostasis in
patients with T2DM and a matched group of healthy control subjects during the
Nijmegen Four Day Marches

Longitudinal study

For objective 1, subjects will undergo blood withdrawal (for measures of
metabolic control and cardiovascular risk) and non-invasive measurements of
vascular function and structure before and after the exercise training. The
Department of Physiology has a long track-record using the proposed techniques
to examine the vasculature and metabolic control in healthy subjects as well as
in patient groups (e.g. spinal cord injury, older subjects, type 1 and 2
diabetes mellitus). These tests involve the repeated inflation of blood
pressure cuffs and application of the non-invasive echo-Doppler technique. We
have never had problems regarding these non-invasive tests nor complaints from
our test subjects. The Department of Physiology has a long and strong history
of performing exercise training studies in healthy volunteers (children,
adolescents, middle-aged and older subjects) as well as various patient groups
(including diabetes mellitus type 1 and 2). Subjects will perform walking
exercise training. This type of exercise training is safe, and not associated
with any health risk.
During the 4-day marches, we will take daily venous blood samples and perform
non-invasive measurements to gain better insight into the hydration status of
subjects (such as body weight changes after exercise). Also, continuous glucose
monitoring will be applied to measure glucose homeostasis. All measures,
therefore, are minimally invasive and not associated with an important health
risk for these patients. Taken together, our study involves minimally and
non-invasive measures, whilst our intervention is believed to have a strong and
potent health benefit for type 2 diabetes patients and will gain important and
novel information about the impact of exercise training in type 2 diabetes
patients.