Molecular biology, gene technology and immunology have extensively clarified the aetiology and pathogenesis of
insulin-dependent diabetes mellitus (
IDDM). It is now obvious that the genetic background of the individual, poorly characterized environmental factors and aggressive autoimmune phenomena in a complex interplay contribute to the progression to clinical
IDDM. The
IDDM risk associated with certain
genetic markers, e.g. the risk alleles at various HLA loci, the most strongly predisposing gene region, and the mechanisms that mediate the genetic impact may differ in different populations. In Finland the accumulated genetic evidence is so convincing that two
IDDM prevention studies have been initiated. One is a population-based prediction and prevention study, while the other is conducted in first-degree relatives of
IDDM patients. Both studies rely on screening of newborn infants for
IDDM susceptibility alleles at the
HLA-DQB1 locus. Meanwhile, in the clinical care of children with
IDDM, the importance of intensified and individualized
insulin therapy in prevention of
diabetic microangiopathy has become increasingly clear, and should be implemented in the care of most paediatric patients.