Clinical feature: 

Definition: Diabetes mellitus is characterizes by impared glucose metabolism due to inadequate insulin secretion or insulin resistance.

Pathogenesis: Only in some few cases diabetes is caused by a monogenetic autosomal dominant form. In most cases diabetes is the result of a polygenetic disposition along with environmental influences. In these cases only risk factors can be defined by molecular testing.

Epidemiology: The prevalence of type 1 diabetes remained nearly constant in the past decades. But the frequency of type 2 diabetes is still increasing and it reached 10% in some developed countries. Environmental factors contribute a lot to the development of type 2 diabetes but it is obvious that hereditary factors contribute too. This is especially true for late omplications of diabetes. These complications are an increasing health problem. Diabetic retinopathy is a common reason for aquired blindness and about 50% of patients on dialysis are diabetics.

Diagnostics: 

Strategy: The type of diabetes has to be established first. In cases with not secure type 1 diabetes the possibility of MODY-diabetes should be checked. If this is not the case the estimation of molecular genetic risk factors can be considered.

Literature: 

Fajans SS et al. (2001) Molecular mechanisms and clinical pathophysiology of maturity-onset diabetes of the young.
Horikawa Y et al. (2000) Genetic variation in the gene encoding calpain-10 is associated with type 2 diabetes mellitus.
Ek J et al. (2001) Studies of the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene in relation to insulin sensitivity among glucose tolerant caucasians.