Diabetes and its complications pose a major health-care burden worldwide and present major challenges to patients, health-care systems, and national economies. The World Health Organization estimates that between 2000 and 2030, the world population will increase by 37% and the number of people with diabetes will increase by 114% . Asia will be the major site of a rapidly emerging diabetes epidemic based on population growth, an increase in the elderly population (> 65 years of age), and the rate of urbanisation . India and China will remain the two countries with the highest numbers of people with diabetes (79·4 million and 42·3 million, respectively) by 2030 . In Malaysia, the prevalence of diabetes has escalated from 6.3% in 1986, to 8.3% in 1996, and to 14.9% in 2006 . One in six Malaysians above the age of 30 years old has diabetes . The dramatic increase in the prevalence of diabetes may be due primarily to the rise in obesity in Malaysia during the past decade, which has been found to be associated with rapid urbanization [2, 3].
Research has shown that the provision of diabetes education by healthcare professionals on medications, diet, exercise, home glucose monitoring, foot care, and treatment modifications have improved clinical outcomes and the quality of life of patients [4–6]. Although knowledge alone does not guarantee a change in behaviour or lead to effective self-management , the assessment of diabetes-related knowledge is an important step towards providing individualize diabetes education programs and to evaluate the effectiveness of such interventions .
A literature search revealed that several instruments for assessing diabetes knowledge have been developed: the Michigan Diabetes Knowledge Tool (MDKT) , the Diabetic Knowledge Questionnaire (DKQ) [10, 11], the Diabetes Knowledge Assessment (DKN) scale , the Revised Diabetes Knowledge Scale , the PedCarbQuiz (PCQ)  and the Diabetic Numeracy Test (DNT) . Most of these instruments were developed and validated in the United States [9–11, 14, 15], whilst others were developed and validated in Australia  and the United Kingdom . The earliest instrument, the MDKT was developed and validated in the 1970s . Most of these instruments were developed in the English Language [9–11, 14, 15]. However, several instruments have since been translated to other languages such as Spanish [10, 11], Portuguese  and Bahasa Malaysia [18, 19].
These instruments varied widely in their assessment objectives. The MDKT assessed knowledge on general issues and insulin use , the DKQ assessed general diabetes knowledge [10, 11], the PCQ assessed carbohydrate food recognition, carbohydrate food counting and the incorporation of carbohydrate counting in calculating insulin dose , whilst the DNT measured numeracy skills for diabetes (food label interpretation, calculation of insulin dose based on blood, glucose and carbohydrate corrections) .
The population in which these instruments were assessed varied between studies. Instruments were validated in adults with type 1 or type 2 diabetes [9, 15], in adults with type 2 diabetes only [10, 11], or in adolescents or children with type 1 diabetes [14, 15].
Patient's knowledge on diabetes, hypertension and hyperlipidaemia and its medications can be used as one of the outcome measures to assess the effectiveness of educational intervention. In Malaysia, two instruments: the Orang Asli-Diabetes Knowledge Questionnaire (OA-DKQ)  and the MDKT  have been translated into Bahasa Malaysia and validated. The OA-DKQ assesses diabetes-related knowledge whilst the MDKT assesses general diabetes knowledge and insulin use. However to date, no instrument that assesses knowledge on other cardiovascular metabolic risk factors such as hypertension and hyperlipidaemia, in addition to diabetes knowledge has been developed and validated in Malaysia. Therefore, the aim of this study was to develop and validate a comprehensive questionnaire to assess patient's knowledge on diabetes, medications, and other cardiovascular metabolic risk factors which included hypertension and hyperlipidaemia, for use by Malaysians with type 2 diabetes mellitus.