Diabetes is typically described as type 1 and type 2 diabetes. However, in 2018 a study from Sweden defined five new subtypes of adult-onset diabetes based on the underlying mechanism: severe autoimmune diabetes (SAID), severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), mild obesity-related diabetes (MOD) and mild age-related diabetes (MARD). SAID includes type 1 diabetes and latent autoimmune diabetes in adults (LADA), while the remaining four denote type 2 diabetes. The most prevalent subtype is MARD.¹ Whether the known modifiable risk factors for diabetes differ among these subtypes is not yet well-established.

A new study published in the journal Diabetology has for the first time shown that obesity during childhood is associated with higher risk of four out of the five subtypes of adult-onset diabetes.²

Researchers from Bristol University in the UK, Sun Yat-Sen University in China and the Karolinska Institute in Sweden collaborated on this study to investigate the impact of childhood obesity on different subtypes of adult-onset diabetes. Data for childhood body size were extracted from a genome-wide association study of 453,169 Europeans who self-reported body size (thinner, about average, and plumper) at age 10 years in the UK Biobank study. More than 200 genetic mutations for childhood body size were identified and linked to the various subtypes of diabetes. Data from two genome-wide association studies from Europe involving adults newly diagnosed diabetes, or without diabetes was used to identify the genetic mutations. The Mendelian randomisation method was used to analyse the association of genetically predicted childhood body size with different diabetes subtypes.

Results showed that being overweight or obese in childhood was associated with 62% higher risk of latent autoimmune diabetes in adults (LADA) with odds ratio (OR) of 1.62. The risk of severe insulin-deficient diabetes (SIDD) was doubled with OR of 2.11, while the risk of severe insulin-resistant diabetes (SIRD) increased nearly three times with OR 2.76. The odds of having mild obesity-related diabetes (MOD) increased 7-folds with OR of 7.30. However, mild age-related diabetes (MARD) showed no such association with childhood obesity (OR 1.06).

Childhood obesity is known to predispose to type 2 diabetes in adulthood characterised by insulin resistance. This study shows that childhood obesity is a risk factor for all subtypes of adult-onset diabetes, including those due to autoimmunity and insulin deficiency, except age-related diabetes. Hence, prevention of obesity during childhood is of utmost importance for better long-term health.

References

1. Ahlqvist E, et al. Novel subgroups of adult-onset diabetes and their association with outcomes: a data-driven cluster analysis of six variables. Lancet Diabetes Endocrinol. 2018 May;6(5):361-369. doi: 10.1016/S2213-8587(18)30051-2.
2. Wei Y, et al. Childhood adiposity and novel subtypes of adult-onset diabetes:a Mendelian randomisation and genome-wide genetic correlation study. Diabetologia. 2023 Feb 27. doi: 10.1007/s00125-023-05883-x.