Diabetes and 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. However, relatively little is known about the immediate
effect of walking exercise training in T2DM.
When walking exercise is performed for prolonged periods, such as during the
Nijmegen 4-Day marches, subjects may develop a fluid- or electrolyte imbalance.
In a series of previous experiments, we found that fluid- and electrolyte
imbalance occurs more often in men, older subjects and subjects with
overweight/obesity. Because of these risk factors, T2DM patients may be at risk
for developing fluid- and electrolyte imbalance compared to healthy controls.
Moreover, relatively little is known about the impact of prolonged walking
exercise on glucose levels, which may be importantly influenced by this type of
exercise. We also want to include a group of Type 1 Diabetes Mellitus (T1DM)
patients. Similar to T2DM, exercise training has potent cardioprotective
effects, whilst relatively little is known about the acute effects of exercise.
Whether T1DM is associated with fluid- and electrolyte imbalance is currently
unknown.

The primary aim of this study is to assess the impact of prolonged walking on
fluid- and electrolyte balance in 32 patients with T2DM, compared with a
matched group of 32 healthy control subjects, and 32 patients with T1DM, during
the Nijmegen Four Day Marches. As a secondary aim, we will examine glucose
homeostasis during prolonged walking exercise in a subgroup of T2DM, T1DM and
controls.

Observational study

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). In addition, continuous
glucose monitoring will be applied to measure glucose homeostasis as a pilot
study in a subgroup of 10 T2DM patients, 10 healthy control subjects, and 10
T1DM patients. For organization purposes, this will be performed a few weeks
before the 4-day marches. All measures, therefore, are minimally invasive and
not associated with an important health risk for these patients, and will
provide important and novel information about the impact of walking exercise in
patients and controls.