Ganoderma lucidum (L) is considered an effective medicinal mushroom. The main goal of this research was to investigate whether the beneficial effects of G. lucidum found in various in vitro or animal studies can be translated to chronic metabolic diseases such as diabetes in humans. Here, we present a case study of a person with diabetes after treatment with G. lucidum and provide important information on fasting blood glucose (FG) levels, glycated hemoglobin (HbA1c), lipid profile, and various other blood parameters. After taking G. lucidum hot water extract for three months, FG levels decreased from 198 mg/dL to 177.3 mg/dL. HbA1c fell by 1.5%. Serum total cholesterol (TC) decreased from 210 to 170 mg/dL, and triglyceride (TG) levels decreased from 220 to 150 mg/dL, while serum high-density cholesterol (HDL-C) increased from 25 to 35 mg/dL. Low-density cholesterol (LDL-C) only decreased by 9 mg/dL. Serum creatinine, alkaline phosphatase (ALP), alanine aminotransferase (ALT), and total bilirubin levels were not changed. Therefore, it is concluded that G. lucidum hot water extract had antidiabetic and antidyslipidemic effects without affecting hepatorenal functions.