Synergistic effect of novel chitosan combined metformin drug on streptozotocin-induced diabetes mellitus rat

•The novel T. ramosus chitosan was derived and employed in diabetic studies.•The high influence on biocompatibility was found in drug combination.•Antioxidant effect variations based on different solvents were revealed.•Structural and functional properties of chitosan/metformin composite was revelled.•Hence, the composite reduce cost, frequent consumption and overdosing effect.