Objective: T2DM is a metabolic disorder characterized by insulin resistance and relative insulin deficiency, resulting in hyperglycemia. Nicotine (one of the active components in tobacco plants) can reduce oxidative stress, excessive inflammation and increase insulin secretion; It may improve insulin sensitivity and pancreatic β cells function. This research aimed to investigate the effects of tobacco leaf ethanol extract toward HOMA IR and β in T2DM rat model. Methods: This study examined the effect of ethanol extract of Nicotiana tabacum leaves on the Homa IR and β of male 8-10 weeks old diabetic Wistar rats. Measurement of Homa IR and β requires data on fasting blood sugar (FBG) and insulin level. Diabetes was induced by high-fat diet for 16 days and intraperitoneal administration of 22.5 mg Streptozotocin per kg of body weight (BW). FBG level was measured, and the criteria used for diabetes was above 180 mg/dL. Four groups of diabetic rats and one group of normoglycaemic rats (n = 5) were used for the study. Sham and STZ-HFD Groups served as non-diabetic and diabetic controls, respectively. Groups P1, P2, and P3 received tobacco leaf extract of 90, 180, 270 mg/kg body weight respectively for 27 days. Weekly FBG, along with serum C-Peptide levels at day 27 were measured. Results: Significantly higher HOMA β score was achieved at dose of 180 and 270 mg/kg BW (Tukey HSD, p = 0.003 and 0.034, respectively). No statistical significance of HOMA IR difference was reported in all treatment group compared to STZ-HFD group (Mann-Whitney, p > 0.05). However, Group P1, P2 and P3 exhibit lower HOMA IR Score compared to STZ-HFD group (31%, 9%, and 45% lower HOMA IR score, respectively). Conclusion: The administration of tobacco leaf ethanol extract on T2DM reduce insulin resistance (HOMA IR) and improve β cell function to secrete insulin (HOMA β).