In early diabetes mellitus (between 2 weeks and 2 months after induction) an increase of neurofilament 200 kDa (NF200, a marker for sensory myelinated neurons) and tyrosine‐hydroxylase (TH, marker of the sympathetic fibres) protein content could be found in the left ventricular wall and in the interventricular septum compared to control animals. This evidence concerns the gene TH and diabetes mellitus.