In this modern era, various degenerative diseases were growing, one of which was diabetes mellitus which was characterized by an increase in blood glucose and occurs in the elderly. One of the non-pharmacological ways to treat high glucose levels in the elderly with diabetes mellitus was by decoction of bay leaves. This study aimed to determine the effect of bay leaf decoction on blood glucose levels in the elderly with diabetes mellitus. The design of this study used one group pretest-posttest design. The population in this study were all the elderly with diabetes mellitus in Sumberwaru Hamlet, Kembangsri Village, Ngoro District, Mojokerto Regency as many as 20 people. The sampling technique of this research was purposive sampling so that the research sample was 20 people. Research instrument used SAP and digital glucometer. Data analysis used paired sample t test. The results of this study suggested that before consuming boiled bay leaves, the average blood glucose level of respondents before boiling bay leaves was 209.8 mg/dL, after decoction of bay leaves decreased to 145.1 mg/dL, the average decrease was 64.7 mg/dL. The results of the paired sample t-test suggested that p-value = 0.000 with = 0.05 so that H1 was accepted, meaning that there was an effect of bay leaf decoction on blood glucose levels in the elderly with diabetes mellitus in Sumberwaru Hamlet, Kembangsri Village, Ngoro District, Mojokerto Regency. The content of bay leaves is known to contain flavonoids that can inhibit glucose reabsorption from the kidneys. Blood glucose levels are influenced by age, diet, exercise habits. Researchers provide education on limiting the consumption of foods and beverages with a high glycemic index so that blood glucose levels decrease.