Type I diabetes (DM I) in caused by immune mediated destruction of pancreatic beta cells (insulinitis). This process reduces during months to years residual mass of beta cell before disease onset. Both genetic and environmental factors are involved in the disease pathogenesis. Autoimmune insulinitis is an asymptomatic process, but it can detect by immunological markers and functional tests. The article in focused on possible early diagnosis of the autoimmune insulinitis and thus on prediction of typeI diabetes bymeans of genetic riskanalysis andimmunological andfunctional evaluation in the risk group of the first-degree relatives diabetic patients. Suggested prediction scheme includes further follow up in relation to the individual genetic risk investigates one of the possibilities of secondary prevention of DM I by administration of nicotinamide.

        Key words: diabetes mellitus type I - IDDM - autoimmune insulitis - prediction and prevention of diabetes