Population-based assessment of a biomarker-based screening pathway to aid diagnosis of monogenic diabetes in young-onset patients
UNITED Study Team
American Diabetes Association
Objective: Monogenic diabetes, a young-onset form of diabetes, is often misdiagnosed as Type 1 diabetes, resulting in unnecessary treatment with insulin. A screening approach for monogenic diabetes is needed to accurately select suitable patients for expensive diagnostic genetic testing. We used C-peptide and islet autoantibodies, highly sensitive and specific biomarkers for discriminating Type 1 from non-Type 1 diabetes, in a biomarker screening pathway for monogenic diabetes. Research Design and Methods: We studied patients diagnosed ≤30y, currently <50y, in two UK regions with existing high detection of monogenic diabetes. The biomarker screening pathway comprised 3 stages: 1) Assessment of endogenous insulin secretion using urinary C-peptide/creatinine ratio (UCPCR); 2) If UCPCR≥0.2nmol/mmol, measurement of GAD and IA2 islet autoantibodies; 3) If negative for both autoantibodies, molecular genetic diagnostic testing for 35 monogenic diabetes subtypes. Results: 1407 patients participated (1365 no known genetic cause, 34 monogenic diabetes, 8 cystic-fibrosis-related diabetes). 386/1365(28%) had UCPCR≥0.2nmol/mmol. 216/386(56%) of these patients were negative for GAD and IA2 and underwent molecular genetic testing. 17 new cases of monogenic diabetes were diagnosed (8 common MODY (Sanger sequencing), 9 rarer causes (next generation sequencing)) in addition to the 34 known cases (estimated prevalence of 3.6% (51/1407) (95%CI: 2.7-4.7%)). The positive predictive value was 20%, suggesting a 1-in-5 detection rate for the pathway. The negative predictive value was 99.9%. Conclusions: The biomarker screening pathway for monogenic diabetes is an effective, cheap, and easily implemented approach to systematically screening all young-onset patients. The minimum prevalence of monogenic diabetes is 3.6% of patients diagnosed ≤30y.
This study was funded by the Department of Health and Wellcome Trust Health Innovation Challenge Award (HICF-1009-041; WT-091985). ATH and SE are Wellcome Trust Senior Investigators. ATH is an NIHR Senior Investigator. BS, ATH, MH, SE, and BK are core members of the NIHR Exeter Clinical Research Facility. EP is a Wellcome Trust New Investigator. TM is supported by NIHR CSO Fellowship. JP is partly funded by the NIHR Collaboration for Leadership in Applied Health Research and Care for the South West (PenCLAHRC).
This is the author accepted manuscript. The final version is available from the American Diabetes Association via the DOI in this record.
Vol. 40(8), pp. 1017-1025