Glucose transporter-4 on peripheral blood mononuclear cells in conditioned vs. sedentary college students

Abstract

Glucose transporter 4 (GLUT-4) plays a key role in the pathophysiology of type 2 diabetes. GLUT-4 is upregulated in response to exercise, enhancing cellular glucose transport in skeletal muscle tissue. This mechanism appears to remain intact in individuals with insulin resistance. There is evidence of increased translocation of GLUT-4 and increased transcription of SLC2A, the gene which codes for GLUT-4. Details of the mechanism are poorly understood and are challenging to study due to the invasive nature of muscle biopsy. Peripheral blood mononuclear cells (PBMC) have documented insulin-sensitive GLUT-4 activity and may serve as a proxy tissue for studying skeletal muscle GLUT-4. The purpose of this study was to investigate whether GLUT-4 on PBMC is affected by exercise in a similar fashion to myocytes. Additionally, correlations between PBMC GLUT-4 and common indicators of insulin resistance and dietary patterns were examined. The results show a trend toward higher PBMC GLUT-4 levels in conditioned athletes than in their sedentary counterparts, similar to what has been documented in myocytes. Females were shown to have higher PBMC GLUT-4 levels than males. SLC2A4 mRNA analysis demonstrates a difference in mean gene expression between the conditioned and sedentary participants. Correlations between levels of PBMC GLUT-4 and hemoglobin A1c (HbA1c), glucose, insulin, HOMA-IR, BMI, or body fat were not detected. Relationships between specific nutrients and GLUT-4 were also not detected. This study provides evidence to support exploration of PBMC as a proxy tissue for studying GLUT-4 response to exercise or other non-insulin factors. This could provide important treatment avenues for individuals with insulin resistance and type 2 diabetes.