Objective: This study was conducted to evaluate the hypoglycemic effect and safety of herbal extracts in patients with type 2 diabetes mellitus.Methods: We investigated 19 hospitalized patients with type 2 diabetes mellitus who were administered Banhasasim-tang (BST), Gumiganghwal-tang (GGT), or Pyeongwee-san (PWS) at Kyung Hee University Korean Medical Hospital for at least three days between January 2012 and December 2021. Their clinical characteristics and laboratory tests were reviewed retrospectively. The glucose-lowering effect of the herbal extracts was assessed by comparing blood glucose levels, including fasting blood sugar (FBS), two-hour postprandial glucose (PP2) levels, and glycated hemoglobin levels. To evaluate the safety of the herbal extract, liver function test and kidney function test results were compared, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine (Cr).Results: After taking herbal extracts, PP2 and HbA1c levels significantly decreased from 205.82 mg/dL to 171.41 mg/dL and 7.58% to 6.62%, respectively. The safety profile reported no significant difference after taking herbal extracts.Conclusions: BST, GGT, and PWS may have hypoglycemic effects in patients with type 2 diabetes mellitus taking hypoglycemic medication.