Disentangling the heterogeneity of adulthood-onset non-autoimmune diabetes: a little closer but lot more to do

Unveiling Diabetes: Categories, Genetics, Diagnostics, Treatments, and Future Horizons

Diabetes mellitus is a global epidemic affecting millions of individuals worldwide. This comprehensive review aims to provide a thorough understanding of the categorization, disease identity, genetic architecture, diagnosis, and treatment of diabetes. The categorization of diabetes is discussed, with a focus on type 1 and type 2 diabetes, as well as the lesser-known types, type 3 and type 4 diabetes. The geographical variation, age, gender, and ethnic differences in the prevalence of type 1 and type 2 diabetes are explored. The impact of disease identity on disease management and the role of autoimmunity in diabetes are examined. The genetic architecture of diabetes, including the interplay between genotype and phenotype, is discussed to enhance our understanding of the underlying mechanisms. The importance of insulin injection sites and the insulin signalling pathway in diabetes management are highlighted. The diagnostic techniques for diabetes are reviewed, along with advancements for improved differentiation between types. Treatment and management approaches, including medications used in diabetes management are presented. Finally, future perspectives are discussed, emphasizing the need for further research and interventions to address the global burden of diabetes. This review serves as a valuable resource for healthcare professionals, researchers, and policymakers, providing insights to develop targeted strategies for the prevention, diagnosis, and management of this complex disease.

Role of Actionable Genes in Pursuing a True Approach of Precision Medicine in Monogenic Diabetes

Monogenic diabetes is a genetic disorder caused by one or more variations in a single gene. It encompasses a broad spectrum of heterogeneous conditions, including neonatal diabetes, maturity onset diabetes of the young (MODY) and syndromic diabetes, affecting 1-5% of patients with diabetes. Some of these variants are harbored by genes whose altered function can be tackled by specific actions ("actionable genes"). In suspected patients, molecular diagnosis allows the implementation of effective approaches of precision medicine so as to allow individual interventions aimed to prevent, mitigate or delay clinical outcomes. This review will almost exclusively concentrate on the clinical strategy that can be specifically pursued in carriers of mutations in "actionable genes", including ABCC8, KCNJ11, GCK, HNF1A, HNF4A, HNF1B, PPARG, GATA4 and GATA6. For each of them we will provide a short background on what is known about gene function and dysfunction. Then, we will discuss how the identification of their mutations in individuals with this form of diabetes, can be used in daily clinical practice to implement specific monitoring and treatments. We hope this article will help clinical diabetologists carefully consider who of their patients deserves timely genetic testing for monogenic diabetes.

Stratification of Type 2 Diabetes by Age of Diagnosis in the UK Biobank Reveals Subgroup-Specific Genetic Associations and Causal Risk Profiles

The pathogenesis of type 2 diabetes (T2D) might change with increasing age. Here, we used a stratification based on age of diagnosis to gain insight into the genetics and causal risk factors of T2D across different age-groups. We performed genome-wide association studies (GWAS) on T2D and T2D subgroups based on age of diagnosis (<50, 50-60, 60-70, and >70 years) (total of 24,986 cases). As control subjects, participants were at least 70 years of age at the end of follow-up without developing T2D (N =187,130). GWAS identified 208 independent lead single nucleotide polymorphism (SNPs) mapping to 69 loci associated with T2D (P < 1.0e-8). Among others, SNPs mapped to CDKN2B-AS1 and multiple independent SNPs mapped to TCF7L2 were more strongly associated with cases diagnosed after age 70 years than with cases diagnosed before age 50 years. Based on the different case groups, we performed two-sample Mendelian randomization. Most notably, we observed that of the investigated risk factors, the association between BMI and T2D attenuated with increasing age of diagnosis. Collectively, our results indicate that stratification of T2D based on age of diag-nosis reveals subgroup-specific genetics and causal determinants, supporting the hypothesis that the pathogenesis of T2D changes with increasing age.