Chitosan (COS) is a natural product. It used as a dietary fiber.  We explored the impact of chitosan administration in case of nicotine toxicity in adult healthy and corresponding diabetic male rats. Eighty mature male albino rats, weighing 190±10 g, were distributed into two sections healthy and diabetic section. Each section separated into 4 groups each one includes 10 rats, group1: control group, group2: orally administrated, COS, group3: administrated nicotine and group4: administrated both COS and nicotine. The experiment lasted 6 weeks. Diabetes induction with STZ caused significant increase in diabetic biomarker, serum glucose level and HOMA-IR. With a strong decline in insulin, liver glycogen as well as in liver glucokinase enzyme activity. Nicotine worsened the diabetic biomarkers. COS administration caused an ameliorative effect on these diabetic biomarkers that caused by diabetes alone or with nicotine. Diabetes and nicotine caused increase in TAGs, TC, LDL-C, VLDL-C, RF and AI with diminished HDL-C level. COS significantly improved the lipids profile in healthy and diabetic groups. Diabetes induction as well as nicotine injection increased ALT and AST activities and decreased the serum albumin, while COS improved the effects of nicotine and diabetes. Diabetes increased serum creatinine, urea and urine albumin. Also, decreased urine urea and creatinine. Nicotine worsened the kidney function tests in both healthy and diabetic rats. COS improved the renal function. Diabetes and nicotine decreased SOD and increased MDA activities. COS increased SOD and decreased MDA. Diabetes and nicotine increased the DNA fragmentation. COS protected the DNA from damage. Finally, the study demonstrated that COS have antidiabetic, antioxidant and antitoxic effects.