Cell-mediated immunity to insulin: A new criterion for differentiation of diabetes mellitus?

Any classification is a step forward and it should help to determine the reason, the course, the prognosis, the treatment of a disease. The current classification of diabetes mellitus (DM) is really very convenient for work, but it has some drawbacks, and the absence of differentiation of type 2 diabetes is the main. The problem is the absence of an adequate criterion, based on pathogenesis for differentiation.We suppose that cell mediated immunity (CMI) to insulin plays the central role in the diabetes genesis. Autoimmune process may be triggered by viruses family Paramyxoviridae, in 10–20% of type 1 diabetes patients the disease is a consequence of direct cytotoxic effect of other viruses to the islet cells of pancreas. In acute phase of viral infection (measles, mumps, parainfluenza) CMI against viruses is developed, in some patients CMI to insulin appeared. We suppose that autoimmune reactions in these cases are the result of cross reaction between viral antigens and insulin. The majorities of patients suppress these reactions and recover from acute infection diseases with the antiviral immunity development and without any complications. Other patients are not able to suppress autoimmune reactions to insulin and pathological process is triggered. Type 1A diabetes is a result of direct CMI to insulin, and this process is responsible for beta-cells destruction; may be type 1B DM is due to the direct cytotoxic effect of other viruses or toxins to them.Some patients with acute viral infection cannot destroy the aggressive clone and they suppress autoimmune reaction to insulin by prostaglandin synthesizing cells (PGSC) or сells with histamine receptors (CHR). As a result of this process the insulin resistance is developed, because these cells or their cytokines form a block to the insulin receptors not only on immunocompetent cells, but in insulin sensitive tissues too.Patients with different reactions to insulin have different courses and outcomes of DM. We suppose that CMI to insulin is acceptable criterion for differentiation of DM, for identifying high risk group of patients in whom DM or its complications may develop. Moreover, prophylactic measures for decreasing of insulin resistance by nonsteroid anti-inflammatory drugs or histamine H2 receptor antagonists in persons with high activity of PGSC or CHR respectively can give good results.Furthermore, our hypothesis explains the initial reason for insulin resistance development, accordingly, it explains the reason for metabolic syndrome and atherosclerosis.