Correlation between Serum 25 (OH) D Levels with Insulin Resistance and Metabolic Associated Fatty Liver Disease - A Retrospective Study based on Chinese Patients with Newly Diagnosed Type 2 Diabetes Mellitus.

Aims: The objective of this study was to investigate the correlation between serum 25 hydroxyvitamin D [25(OH)D] levels and insulin resistance, as well as metabolic associated fatty liver disease (MAFLD) in newly diagnosed with type 2 diabetes mellitus(T2DM) patients.

Method: A retrospective analysis was conducted on 491 T2DM patients who were newly diagnosed between January 2017 and August 2022 at Peking University International Hospital. These patients were categorized into three groups based on their 25(OH)D levels.

Results: The prevalence of MAFLD was significantly elevated in both the Vitamin D(VD) deficiency group and the VD insufficiency group compared to the VD sufficiency group (χ2 = 6.51, p<0.05). The patients in the VD sufficiency group had lower levels of insulin resistance，as assessed by the homeostasis model assessment when compared to the VD deficiency group and the VD insufficiency group (F = 8.61，p < 0.05). Additionally, the VD sufficiency group demonstrated higher levels of β cell function in comparison to the other two groups(p<0.05， respectively). (2) A significant negative correlation was observed between 25(OH)D levels and insulin resistance, as assessed by the homeostasis model assessment in T2DM patients(r=-0.33，p<0.05 for females; r=-0.32，p<0.05 for males). (3) In male patients, 25(OH)D was identified as a protective factor against MAFLD(OR = 0.42;95%CI:0.19-0.95;p<0.05). Meanwhile，in female patients, 25(OH)D was also associated with a reduced risk of MAFLD(OR = 0.35;95%CI 0.17-0.89;p<0.05). Additionally, the study determined that the threshold values for 25(OH)D were 15.06 ng/ml in female patients and 18.79 ng/ml in male patients for predicting MAFLD.

Conclusion: In newly diagnosed with T2DM patients, the level of 25(OH)D may be related to insulin resistance and β cell secretion function independently and VD deficiency is an independent risk factor for MAFLD in patients with newly diagnosed T2DM.