A total of 80 poorly controlled type 2 diabetes patients with glycohemoglobin ≥ 9% from Endocrinology and Metabolism clinics or Internal Chinese Medicine clinics will be enrolled in this randomized double-blind placebo-controlled trial. Subjects will be randomly assigned to receive either YH1 (6 g) or the placebo three times per day for 12 consecutive weeks. All subjects in both groups will also continuously receive their oral hypoglycemic agents without any dose or medicine change. During this 12-week period, the glycohemoglobin, fasting plasma glucose, 2h postprandial glucose, waist circumference, body weight, and body mass index will be assessed. In addition, insulin resistance, β -cell function, lipid profile, liver and renal function will also be evaluated. Independent statisticians will perform the data analysis at the end of the trial.