Type 2 diabetes mellitus (T2DM) is characterized by chronic
hyperglycemia, which induces neuron, kidney and eye dysfunction.
Hyperglycemia is also a risk factor for dementia. T2DM
also causes brain insulin resistance, oxidative stress and cognitive
impairment. Futhermore, oxidative stress causes a complex dysregulation
of cell metabolism resulting in insulin resistance and
beta cell dysfunction. Alzheimer’s Disease (AD) is the most
common form of dementia among older people worldwide, and
oxidative stress is an important pathogenic factor in AD. Oxygen
metabolism generates free radicals such as hydroxylradical, superoxide
radical, and reactive nitrogen species, inducing ROS. An
imbalance between oxidant and antioxidant agents could generate
oxidative stress, which damages macromolecules and disrupts the
reduction/oxidation (redox) signaling. Mitochondria contain
many redox enzymes, and generate ROS when there are inefficiencies
in oxidative phosphorylation. Mitochondrial dysfunction
occurs early and has a primary role in the pathogenesis of AD. T2DM patients show increased incidence of AD, and one
report has shown the role of insulin in that it links T2DM with
AD through mitochondrial alterations, oxidative stress and glucose
metabolism. The insulin effect not only impacts glucose
metabolism, but also has neuroprotective and neuromodulatory
effects.
