Morphologic Changes in Autonomic Nerves in Diabetic Autonomic Neuropathy

Area of Science:

• Endocrinology and Metabolism
• Neurology
• Pathology

Background:

• Diabetic neuropathy is a significant complication of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), increasing patient morbidity and mortality.
• Diabetic autonomic neuropathy (DAN) involves complex autonomic nervous system (ANS) changes, but the precise morphological alterations and mechanisms remain unclear.
• While sympathetic and parasympathetic neuropathy prevalence is similar in T1DM and T2DM, functional correlations differ, suggesting distinct pathological pathways.

Purpose of the Study:

• To investigate the morphological changes in sympathetic and parasympathetic nerves within organs affected by DAN in T1DM and T2DM patients.
• To explore potential differences in the progression of sympathetic versus parasympathetic neuropathy in T2DM, aligning with Ewing's concept.
• To discuss methodologies for evaluating morphological changes in epidermal and gastric intrinsic nerves relevant to DAN.

Main Methods:

• Review of existing literature on morphological changes in autonomic nerves in diabetic neuropathy.
• Discussion of evaluation techniques for epidermal nerve fiber density in skin biopsies.
• Exploration of methods to assess intrinsic nerve morphology within the gastric system.

Main Results:

• Parasympathetic nerve dysfunction appears more severely affected in T2DM patients compared to T1DM patients.
• Evidence suggests parasympathetic neuropathy may precede sympathetic neuropathy in T2DM, potentially due to intrinsic morphological differences.
• Functional correlations between sympathetic and parasympathetic nerve function are observed only in T1DM patients.

Conclusions:

• Morphological evaluation of both sympathetic and parasympathetic nerves is crucial for understanding DAN in T1DM and T2DM.
• The distinct patterns of neuropathy in T1DM and T2DM highlight the need for organ-specific and diabetes-type-specific investigations.
• Further research into the morphological basis of DAN is essential for developing targeted therapeutic strategies.