This project aims to aim to investigate the epidemiology and genetic epidemiology of adult onset IDDM. Specifically, we will: 1) develop uniform diagnostic criteria for classification of the disease; 2) estimate the age- and gender-specific incidence of adult onset IDDM; 3) relate incidence to year (and month) of onset and geographical region within Europe; 4) estimate the frequencies of genetic (i.e. HLA and non-HLA genes) and immunological markers in IDDM patients and normal subjects in European populations; and, 5) relate marker frequencies to IDDM incidence throughout Europe. This study will deliver scientific information in an area that has so far been more or less neglected in the diabetes research world despite the evidence that the majority of new IDDM cases arise in adulthood rather than in children.
The application of uniform classification criteria will provide doctors with accurate information, needed to counsel patients on the risk of adults onset IDDM. The epidemiologic and genetic epidemiologic information generated by IDA is expected to facilitate etiologic studies that might eventually lead to preventive interventions.
Type 1 (insulin-dependent) diabetes mellitus (IDDM) is one of the most common chronics diseases in children and young adults. The long-term complications of IDDM are debilitating and often lead to premature death. Genetic susceptibility, combined with as yet unknown environmental exposures, have repeatedly been implicated in the etiology of IDDM. The appearant necessity of an environmental trigger for the immune responses which eventually destroy the insulin-producing cells of pancreas indicates that IDDM may be preventable. The childhood onset form of IDDM (i.e. ages < 15 years) has been studied extensively. In contrast, the adult onset form of IDDM is poorly characterized although there are reports claiming the majority of occurrences take place in the ages > 15 years. The onset of IDDM in adults is usually slower and less acute. There are other differences, in incidence rates, gender distribution (i.e. a male excess), and the frequencies of genetic and imrnunological markers. Hence, the adult and childhood onset forms may differ aetiologically. Defining these differences is problematic: a significant proportion of occurences in adults represent gestational and Type 2 (non insulin-dependent) diabetes mellitus. Classification is difficult. Patients are treated in diabetes wards, general practises, and sometimes even in obstetrical units. Uniform objective classification criteria suitable for epidemiological studies are lacking.
The IDA study builds on an existing epidemiologic network involving EURODIAB ACE, EURODIAB TIGER, and PARADIGM. Specifically, EURODIAB ACE (Dr Anders Green, Odense) was established as a Concerted Action under the BIOMED 1 Programme to define the epidemiology of IDDM. EURODIAB TIGER was then established under the BIOMED 2 Programme and proposed work to relate the frequencies of high risk genotypes and immune markers to the incidence of IDDM has been funded. The centralized laboratory facility for EURODIAB TIGER (and subsequently IDA) involves PARADIGM (Dr. Polly J. Bingley, London), also established under the BIOMED 2 Programme. IDA originated within EURODIAB ACE when problems related to classification criteria, and a wider network of collaborators, resulted in the need for splitting up coordination and data management for studies of childhood and adult IDDM. However, IDA and EURODIAB TIGER are harmonized: they have coordinated study designs and employ the same laboratory facility. This should greatly facilitate comparisons between childhood and adult onset IDDM.
Type l (insulin dependent) diabetes mellitus Epidemiology, genetic Epidemiology, genetic Epidemiology, Genetic manhers, Immune manhers