Brahmanbaria is a district in east-central Bangladesh lies between 23°57´10" and 23°.95´28" N latitude and between 91°07´00" and 91°11´67"E longitudes. The district is geographically characterized by low-lying land with small hills and hillocks of red soil (Musa and Muhammad., 1998). Total population of Brahmmanbaria is 2,840,498 & density 1,500/km 2 (Bangladesh Census, 2011). This is a culturally riches area. This area is located near the tripura border of india, so cultural knowledge of two countries cross connected by this area. It also comprises heterogeneous habitat including foothills, wetlands, floodplain, and homestead. Railway & junction transition area lies between Bangladesh & India. So biodiversity of this area is quite good. Study area: Brahmmanbaria district (Map) Ethnobotanical data collection and type of data collection Ethnobotanical study carried out from January 2015 to January 2016 following the standard guidelines for ethnobotanical survey (Martin, 1995; Alexiades, 1996). To get the information about the medicinal plants used for the treatment of diabetes from Brahmanbaria, interviews of the key informants (Martin, 1995; Tremblay, 1957) were implemented. Total 452 interviews were conducted in which 264 males and 188 females from different region of study area. The data of medicinal uses have been recorded through semi- structured interviews, focus group discussion and informal conversations (Alexiades, 1996; Chambers, 1994; Martin, 1995). The information obtained was cross- checked with the other informants (Hong et al., 2015). Every informant was interviewed once. Local assistant often helps to understand dialect and traditions. The questionnaire contained no strict questions and informants were allowed to speak spontaneously. in their local language and without pressure (Martin, 1995). General knowledge about diabetes and access of allopathic medicine, social status of Health worker and Allopathic doctor 54 Village doctors 27 Knowledgeable elder 95 informants also discussed. Gender, age, profession, education, and any other information concerning their background were recorded for each informant. The informants were native-born or had been living in the study area for a long General inhabitants (farmers, housewife, fisherman and others) DATA ANALYSIS 163 time. A digital voice recorder was used during interview and photographs of all recorded medicinal plants have been captured from study area. Face to face interviews were conducted for resolving and registering demographic characteristics of respondents. Among the informants age groups of 51–60 was very high compared to other groups and most of them are Muslim. Education levels of the informants were from illiterate up to M.Sc. Degree. Professionally they were mostly farmer, fisherman, day labor, house wife, small shopkeepers, teacher and health worker, village medicine men, allopathic doctors, kobiraj (local traditional healer) etc. The informants were asked to show the plant sample during interview. Voucher specimens for each medicinal plant have been collected and processed using standard herbarium techniques (Hyland, 1972; Alexiades, 1996). The specimens were identified consulting different Floras viz., Hooker, 1872-1897; Prain, 1903; Uddin and Hassan, 2004; Siddiqui et al., 2007c and Ahmed et al., 2008a, 2008b, 2009b, 2009c, 2009d, 2009e. Specimens available at Dhaka University Salar Khan Herbarium (DUSH) were consulted in identifying the collected plant specimens. Voucher specimens have been deposited at Salar Khan Herbarium, Department of Botany, and University of Dhaka. Sample size and demographic data of key informants Informants group No. The frequency of citation was calculated to evaluate the prevalence of one particular plant species used for the treatment of diabetes in relation to the overall citations for all plants. The frequency of citation for a plant was calculated as follows: Frequency of citation for a particular species= (Number of citations for that particular species/ Number of all citations for all species)*100 (Bahmani et al., 2014; Uddin et al., 2014, Uddin et al., 2015). The Fl value is useful for identifying the informants most preferred species in use for treating certain ailments (Friedman et al., 1986). The fidelity level (FL), the percentage of informants claiming the use of a certain plant species for the same major purpose, was calculated for the most frequently reported diseases or ailments as: FL (%) = (Np / N) × 100 Where, Np = number of informants that claim a use of a plant species to treat a particular disease; N = number of informants that use the plants as a medicine to treat any given disease.