South Asians are at a substantially higher risk of type 2 diabetes mellitus (T2DM) compared with white Europeans, especially when living in regions with a westernized lifestyle. South Asians often develop T2DM 5–10 years earlier than westerns, and at a lower body mass index (BMI). This project aims to consider the complete mechanistic pathway from gene to phenotype explaining T2DM development in migrant south Asians, particularly in those with lower age and BMI. Our results will help to develop ethnic-specific strategies to reduce T2DM-risk. I propose a deep phenotyping study of young Nordic and south Asian women living in Norway, with a history of gestational diabetes placing them at high risk of T2DM. Investigations include among others the hyperinsulinemic euglyemic clamp with c-peptide deconvolution, CT-scans, blood, muscle and fat sampels for multi-omics, and randomized controlled trials including lifestyle interventions, GLP-1-analogs and SGLT2-inhibitors. This will enable new or improved treatments that target T2DM defects more precisely, with fewer side effects.