Diabetes mellitus

Diabetic nephropathy (DN) is the leading cause (25%) of chronic renal failure in adults in the western world and has one of the worst survival rates for individuals receiving renal replacement therapy. Typical morphologic features of the disease are thickening of the glomerular basement membrane, mesangial expansion with diffuse or nodular glomerulosclerosis (Kimmelstiel–Wilson nodules), and arteriolar hyalinosis. DN usually develops after 10–15 years of diabetic mellitus and is progressive in nature, resulting in end-stage kidney disease. There is, however, recent evidence that glomerular and tubulointerstitial lesions in DN are to some extent reversible after correction of hyperglycemia. This is not the case, though, for vascular changes. Apart from the typical course of DN, there are a few conditions with an atypical course or symptoms that may result from another renal disease that is superimposed on DN, such as kidney changes in systemic diseases or in immune complex glomerulonephritis; these require a diagnostic kidney biopsy.     

Diabetes mellitus and immunization

Principles of prevention of infectious diseases have been known for several thousands of years. One of the most significant tools of infection prophylaxis is immunization. Vaccines containing thymus-dependent antigens produce massive and complex immune response and feature immunologic memory. That is why they can successfully protect patients with diabetes. Lately, it has been thought by general public and even experts that application of vaccines within national immunization programmes is one of the etiopathogenetic factors in the development of type 1 diabetes mellitus (DM). However, analysis of extensive studies performed by the experts of the Institute for Vaccine Safety proved that there is no positive or negative impact of immunization on the development of type 1 diabetes mellitus. The basic vaccinations recommended for diabetics include immunizations against influenza, pneumococcal infections, tetanus and viral hepatitis B. Other vaccines are administered only after individual assessment of benefits and risks for the diabetic patient. Most often, these are vaccinations against viral hepatitis A, tick-borne encephalitis, meningococcal infections and other infections that put in risk diabetic patients travelling abroad.     

Diabetes mellitus and autoimmunity

Insulin-dependent diabetes is the direct consequence of an autoimmune reaction causing the destruction of the beta cells of the islets of Langerhans in the pancreas. The frequent association of diabetes with other diseases involving the immune system, the detection of circulating antibodies aimed at the islet cells, the occurrence of the disease in subjects with peculiar HLA antigens are as many arguments supporting the immunological hypothesis. The study of animal models of insulin-dependent diabetes (BB rats, NOD mice) now allows demonstrating the autoimmune process. The transient effectiveness of cyclosporin demonstrated in the human disease confirms these data. The prospects of transplantation of the pancreas, of islets or of islet cells in diabetic subjects to compensate for the insulin deficiency therefore raises the double immunological problem of allogenic rejection and of the risk of recurrence of the anti-islet autoimmune disease.     

Diabetes mellitus and microalbuminuria

Microalbuminuria is considered as an independent predictor of cardiovascular morbidity and mortality and is a general marker of endothelial dysfunction. Microalbuminuria is the indicator of the incipient phase of diabetic nephropathy in diabetes mellitus, and especially in the type 1 diabetes mellitus patients. Progressive continuously growing albumin secretion into the urine is a generally recognised criterion for determining the degree of diabetic renal affection. The modern definition of diabetic nephropathy therefore includes increased cardiovascular risk which--if not treated--is accompanied by progressive decrease in renal functions related to diabetic retinopathy. In the case of a positive microalbuminuria result, strict monitoring of diabetes compensation and of systemic pressure is necessary in order to prevent further progression of specific microvascular complications of diabetes. The article provides an overview of epidemiological data and current knowledge of etiopathogenesis of microalbuminuria in diabetic nephropathy.     

Diabetes mellitus and cancer

Although an association between diabetes and cancer was found over 100 years ago, the issue underwent different interpretations over the subsequent decades, and only modern, prospective, epidemiological cohort and case-control studies conducted in several countries have provided reliable evidence of an increased cancer risk in diabetic patients, mainly in those with type 2 diabetes. This risk varies according to the tumor site: it is the greatest for primary liver cancer, moderately elevated for pancreatic cancer, and relatively low for colorectal, endometrial, breast, and renal cancers. The cause of the association is not clear and remains the subject of different hypotheses. The most frequently cited reason is the potential effect of insulin. Found in high concentrations, due to insulin resistance in most patients with type 2 diabetes, this hormone is believed to express a mitogenic effect. This hypothesis needs to be confirmed in appropriately programmed prospective studies, but it may already be helpful in choosing an adequate treatment for type 2 diabetes to achieve optimal metabolic control with a simultaneous reduction in hyperinsulinemia, such as diet, physical exercise, metformin, and acarbose.