## 1 Introduction  
Diabetes mellitus (DM) is a chronic disease that is characterized by hyperglycemia. It has become a globally threatening disease that affected 463 million people (9.3%) in the age group of 18-99 years in 2019 and is predicted to affect 700 million (10.9%) in 2045 [1]. The laboratory tests that are currently used for the diagnosis of DM are fasting blood sugar (FBS), two-hour plasma glucose (2 hG), and glycosylated hemoglobin (HbA1c) [2]. Among these, HbA1c has been recognized as the gold standard for glycemic control. HbA1c indicates glycemic control over one to two months because erythrocytes (RBCs) have a life span of approximately 120 days. However, underlying diseases that shorten the lifespan of RBCs, such as haemoglobin, thalassemia, renal anemia, hemolytic anemia (HA), and liver cirrhosis, affect HbA1c measurement [3]. Glycated albumin (GA), one of the fructosamines, is produced by the nonenzymatic reaction of glucose and albumin and it is specific to albumin glycation rates. Unlike HbA1c, abnormal hemoglobin and impaired metabolism, such as anemia or variant hemoglobin, cannot affect GA levels. GA has a half-life of 14-21 days [4]. Therefore, GA indicates the glycemic status for the previous 2 weeks [5], which is an earlier detection of rapid changes in blood glucose compared to HbA1c [6]. Several methods are used for the measurement of GA levels, including boronate affinity chromatography, immunoassay (radioimmunoassay or enzyme-linked immunosorbent assays), high-performance liquid chromatography, ion-exchange chromatography, capillary electrophoresis [7], refractive index measurement [8], Raman spectroscopy [9], graphene-based aptasensors [10], field effect aptasensors [11], electrochemical aptasensors [12; 13; 14] and other electrophoretic techniques [15]. However, low sensitivity, the need for sophisticated instruments, expense and interference limits the utility of these methods for GA measurements. Therefore, the development of rapid, sensitive, and cost-effective biosensors is required. Short, synthetic, single-stranded DNA or RNA oligonucleotides are known as aptamers. Aptamers have complex, three-dimensional structures and low molecular weight (6-40 kDa) [16]. The advantages of aptamers compromise their ability to be synthesized for mass production: little immunogenicity or toxicity, the capability of immobilization to various surfaces, high tolerance to temperature, ease of transport, greater consistency than antibodies, and alteration of the desired aptamer binding capacity to the target [17]. Among the biosensors for the detection of biomolecules, such as proteins, electrochemical-based aptamer biosensors have emerged as an ultrasensitive, rapid, and cost-effective approach [18; 19]. Electrochemical biosensors transduce the biomolecular reaction into the electrochemical signal via the transducer and quantify the number of antigens in the sample. Label-free detection is proven to be simple, time saving and more applicable than label-based protocols. Different electrochemical biosensors depend on the types of applied signals and responses [20]. Graphene oxide (GO), an oxidized form of graphene, can exhibit a higher affinity in attaching biomolecules through amide bonds. GO has been implied as a transducer in biosensing elements because of its broad surface area, electrical conductivity, high charge transfer, and capability to immobilize different biomolecules [21]. Graphene-based nanomaterials have been widely used in electrochemical sensors because they facilitate electron transfer reactions, thereby generating high signal sensitivity. [PERSON] et al. reported an electrochemical aptasensor with a low LOD (3 ng mL\({}^{-1}\)) [12]. The fabrication is based on the streptavidin (STR)-biotin aptamer reaction, which is simple yet has a prolonged processing time requiring overnight incubation of STR to firmly bind onto the electrode surface.