Beta-Cell Function, Insulin Sensitivity, and Metabolic Characteristics in Young-Onset Type 2 Diabetes Mellitus:...

In this study, we aimed to determine the metabolic characteristics and changes in the early stages of young-onset type 2 diabetes mellitus (YOD) in Koreans.

From the Anam Diabetes Observational Study cohort (2017-2023), the characteristics of newly diagnosed YOD (<40 years of age, n=39) and later-onset (≥40 years of age) type 2 diabetes mellitus (LOD, n=178) were compared at diagnosis and 1 year later. All participants underwent an oral glucose tolerance test at diagnosis and annually thereafter. β-Cell function was determined using the disposition index (DI), calculated as the insulinogenic index×Matsuda insulin sensitivity index (ISI). Insulin sensitivity was determined using ISI and homeostasis model assessment of insulin resistance (HOMA2-IR).

Mean (±standard deviation) age of individuals with YOD was 29.8±6.4 years, and 76.9% were male. YOD patients had higher body mass index (29.8 kg/m2 vs. 27.2 kg/m2, P=0.020), fat mass (30.5 kg vs. 24.1 kg, P=0.011), fatty liver index (65.4 vs. 49.2, P=0.005), and glycosylated hemoglobin (HbA1c) level at diagnosis (9.3% vs. 7.7%, P<0.001) compared with LOD patients. YOD patients exhibited lower insulin sensitivity (ISI: 2.79 vs. 3.26, P=0.008; HOMA2-IR: 2.72 vs. 1.83, P<0.001) and β-cell function (DI) at diagnosis (0.41 vs. 0.72, P=0.003) than LOD patients. Following 1 year of treatment, DI improved by 94% in YOD along with improvement in HbA1c; however, it was still significantly lower than that of LOD (0.64 vs. 0.90, P=0.017).

Individuals with YOD have unfavorable metabolic characteristics, substantially reduced insulin sensitivity, and decompensated β-cell function at disease onset, which persist even after treatment.