**1. Introduction**

According to the International Diabetes Federation, diabetes is one of the largest global health emergencies of the twenty-first century and is the top 10 causes of death globally [1]. Diabetes mellitus (DM) is a disease in which the human body cannot produce sufficient amount of insulin and fails to respond to the hormone insulin that will result to the abnormal increase of glucose level in the blood circulation resulting in hyperglycaemia [2]. It is a complex metabolic disorder which can damage multiple organs in the human body [3]. DM affects or even burdens individual and communities with huge economic cost and leads to a decrease in overall productivity [4]. The complications of DM, especially type 2, can be enhanced by comorbidities such as hypertension, stroke, etc. [5]. Diabetes is the leading problem of kidney failure, lower-limb amputation and also blindness among adults [6]. In Malaysia, diabetes is one of the main public health problems and is closely related to avoidable and premature death [7].

The World Health Organization (WHO) divides the DM into two major categories which are insulin-dependent diabetes mellitus (IDDM) or type 1 diabetes mellitus and non-insulin-dependent diabetes mellitus (NIDDM) or type 2 diabetes mellitus [8]. Approximately 90% of all diabetes cases in both developed and developing countries are NIDDM and can be found mostly in people more than 30 years old [9]. In type 1 DM, the pancreas cannot produce insulin, and the body has to completely rely on the synthetic insulin to reduce the glucose in the blood.

Type 1 DM is common in children, teenager as well as young adult [10]. DM can lead to complications such as diabetic nephropathy, diabetic retinopathy, ischaemic heart disease and many more [11]. The number of people with type 2 DM is increasing in every country with 79% of people with DM living in low- and middle-income countries [12].
