Type 2 diabetes mellitus (T2DM) affects microRNAs (miRNAs) expression that are known as Post-transcriptional repressors of gene expression in plants and animals. This research aimed to investigate the expression levels of miR-34a, miR-126, miR-125a-5p, and miR-29b for diabetes diagnosis, and the effect of α-L-guluronic acid and β-D-mannuronic acid supplementation on the expression pattern of these miRNAs in diabetic rats. Total miRNAs were extracted and evaluated by qRT-PCR method. body weight, fasting insulin levels, food intake and Vitamin D level in four group after 4-week intervention also measured. The analyzes showed significant increase in expression levels of miR-126 and miR-125a-5p, in diabetic control groups (p=0.001). Also, miR-29b was undetectable in the sera of experimental rats. After treatment with β-D-mannuronic acid, the expression level of miR-34a was upregulated in diabetic rats (p=0.026), but α-L-guluronic acid was not significantly effective. Also, expression levels of miR-126 (p=0.026) and miR-125a-5p (p=0.041) were downregulated significantly in diabetic rats, after treatment with β-D-mannuronic acid and, α-L-guluronic acid respectively. these results suggest that use of miR 126 ,125a-5p and miR 34a for diagnosing diabetes is sensible, also we can consider β-D-mannuronic acid as new therapeutic agent for correct disturbance in miRNA profile of diabetic rats.