The hypoglycemic effect of many of the so-called medicinal plants has been approved in many animal models. However, several clinical trials are still underway to test the effect and efficacy of plant extracts on blood sugar control. This study aims to confirm the hypoglycemic effect of ten traditional plants on glycated hemoglobin (HbA1c) and to question the use of these plants in the control of diabetes and their safety in patients with type 2 diabetes. This is an uncontrolled longitudinal study of 22 patients with type 2 diabetes attending the Quilma Health Center (Morocco). These participants agreed after their consent to proceed with the examination of the evolution of their HbA1centre on October 1, 2015, and June 30, 2016, before and after the usual use of medicinal plants. The HbA1c assays were carried out using a hemoglobinometer (MQ 2000 PT / HPLC) in the health center. A semi-directive questionnaire was administered to the patients in order to identify the characteristics of our sample and to examine the medicinal plants used, their mode of use as well as their mode of preparation. The results show that of the ten plants studied, and considered in the literature as hypoglycemic, only three plants showed this effect. Namely Foeniculum vulgare Gaertn (36.3%) Trigonella foenum-graecum (13.3%), and Lupinus albus. (13.85%), For the seven other plants which did not show a hypoglycaemic effect, the cause of the absence of their hypoglycaemic effect could be due to unsuitable conditions of the use of the plant as a natural hypoglycaemic substance. in particular, the choice of the part of the plant used, the stage and season of its picking, its method of preparation, its dose, and its frequency of use. Thus, for each known to have hypoglycaemic power, it is, therefore, useful to seek the optimal conditions for its use.