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The improvement in assays for islet autoantibodies and the development of genetic prediction models has raised the possibility of population screening for individuals at high type 1 diabetes susceptibility. The problem is that the numbers needed to be screened to identify a single case are prohibitive (Figure 6.10) and the absence of an effective treatment means that conventional criteria for screening are not fully satisfied. The TrialNet and other research programmes aims to recruit first degree relatives of probands with type 1 diabetes and as our understanding of heritability develops, the argument for more widespread but focused screening may become stronger.

Figure 6.9 Stages of Type 1 Diabetes as proposed by the Juvenile Diabetes Research Foundation, Endocrine Society and American Diabetes Association and adopted by TrialNet for preventative studies. Autoantibodies are present many years prior to development of symptomatic diabetes (Stage 3). Prior to this those in Stage 1 have normal glucose tolerance and those in Stage 2 varying levels of hyperglycaemia below the diagnostic thresholds of diabetes. Intervention and prevention studies have largely focused on Stage 2 and 3 patients.

Reproduced from Insel RA et al. Diabetes Care 2015; 38: 1964–74 with permission.

Figure 6.10 Lifetime risk of developing Type 1 diabetes (left axis) compared to prevalence of risk in the overall population (right axis). Individuals in the apex have the highest risk of developing diabetes (>75% within 5y) but represent 0.01% (1 in 10,000) of the overall population.

From Dayan CM et al Lancet 2019 with permission.