Published online Jan 25, 2016. doi: 10.4239/wjd.v7.i2.14
Peer-review started: July 24, 2015
First decision: August 25, 2015
Revised: September 14, 2015
Accepted: October 23, 2015
Article in press: October 24, 2015
Published online: January 25, 2016
Processing time: 182 Days and 8.7 Hours
Diabetes mellitus is a common disease and its prevalence is increasing worldwide. In various studies up to 30%-70% of patients present dysfunction and complications related to the gut. To date several clinical studies have demonstrated that autonomic nervous system neuropathy and generalized neuropathy of the central nervous system (CNS) may play a major role. This systematic review provides an overview of the neurodegenerative changes that occur as a consequence of diabetes with a focus on the CNS changes and gastrointestinal (GI) dysfunction. Animal models where diabetes was induced experimentally support that the disease induces changes in CNS. Recent investigations with electroencephalography and functional brain imaging in patients with diabetes confirm these structural and functional brain changes. Encephalographic studies demonstrated that altered insular processing of sensory stimuli seems to be a key player in symptom generation. In fact one study indicated that the more GI symptoms the patients experienced, the deeper the insular electrical source was located. The electroencephalography was often used in combination with quantitative sensory testing mainly showing hyposensitivity to stimulation of GI organs. Imaging studies on patients with diabetes and GI symptoms mainly showed microstructural changes, especially in brain areas involved in visceral sensory processing. As the electrophysiological and imaging changes were associated with GI and autonomic symptoms they may represent a future therapeutic target for treating diabetics either pharmacologically or with neuromodulation.
Core tip: Investigation of the existing literature on diabetes patients with gastrointestinal (GI) symptoms indicates the presence of structural and functional brain changes. This was most consistent in electrophysiological studies, where especially changes in the insula seemed to correlate with GI symptoms. Imaging studies confirmed the electrophysiological findings showing microstructural changes in brain areas involved in visceral sensory processing. Due to these findings, future targets in treatment of GI symptoms in patients with diabetes may be based on modulation of central nervous system reorganisation, either pharmacologically or with afferent nerve stimulation.