Diabetes Mellitus (DM) is a group of metabolic diseases characterized by chronic high blood glucose concentrations (hyperglycemia). When it is left untreated or improperly managed, it can lead to acute complications including diabetic ketoacidosis and non-ketotic hyperosmolar coma. In addition, possible long-term complications include impotence, nerve damage, stroke, chronic kidney failure, cardiovascular disease, foot ulcers, and retinopathy. Historically, universal methods to measure glycemic control for the diagnosis of diabetes included fasting plasma glucose level (FPG), 2-h plasma glucose (2HP), and random plasma glucose. However, these measurements did not provide information about glycemic control over a long period of time. To address this problem, there has been a switch in the past decade to diagnosing diabetes and its severity through measurement of blood glycated proteins such as Hemoglobin A1c (HbA1c) and glycated albumin (GA). Diagnosis and evaluation of diabetes using glycated proteins has many advantages including high accuracy of glycemic control over a period of time. Currently, common laboratory methods used to measure glycated proteins are high-performance liquid chromatography (HPLC), immunoassay, and electrophoresis. HbA1c is one of the most important diagnostic factors for diabetes. However, some reports indicate that HbA1c is not a suitable marker to determine glycemic control in all diabetic patients. GA, which is not influenced by changes in the lifespan of erythrocytes, is thought to be a good alternative indicator of glycemic control in diabetic patients. Here, we review the literature that has investigated the suitability of HbA1c, GA and GA:HbA1c as indicators of long-term glycemic control and demonstrate the importance of selecting the appropriate glycated protein based on the patient's health status in order to provide useful and modern point-of-care monitoring and treatment.

In this research, a new electrochemical biosensor was constructed for the glucose detection. Iron oxide nanoparticles (FeO) were synthesized through co-precipitation method. Polyvinyl alcohol-FeO nanocomposite was prepared by dispersing synthesized nanoparticles in the polyvinyl alcohol (PVA) solution. Glucose oxidase (GOx) was immobilized on the PVA-FeO nanocomposite via physical adsorption. The mixture of PVA, FeO nanoparticles and GOx was drop cast on a tin (Sn) electrode surface (GOx/PVA-FeO/Sn). The FeO nanoparticles were characterized by X-ray diffraction (XRD). Also, Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM) techniques were utilized to evaluate the PVA-FeO and GOx/PVA-FeO nanocomposites. The electrochemical performance of the modified biosensor was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Presence of FeO nanoparticles in the PVA matrix enhanced the electron transfer between enzyme and electrode surface and the immobilized GOx showed excellent catalytic characteristic toward glucose. The GOx/PVA-FeO/Sn bioelectrode could measure glucose in the range from 5 × 10 to 30 mM with a sensitivity of 9.36 μA mM and exhibited a lower detection limit of 8 μM at a signal-to-noise ratio of 3. The value of Michaelis-Menten constant (K) was calculated as 1.42 mM. The modified biosensor also has good anti-interfering ability during the glucose detection, fast response (10 s), good reproducibility and satisfactory stability. Finally, the results demonstrated that the GOx/PVA-FeO/Sn bioelectrode is promising in biosensor construction.

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We present a study of the effect of graphene–PANI nanocomposites on the sensitivity of the urea and glucose multisensory. We used an electroctrochemical multisensor based on two electrodes located in a reservoir with two separate channels. The urease and glu-cose oxidase (GOD) were employed for detecting the urea and glucose, respectively. We characterized the graphene and graphene-PANI samples with X-ray Diffraction (XRD) analysis and scanning electron microscopy (SEM) observations. We further performed the Cyclic voltammetry and Amperometry tests. The collected experimental results revealed that the intensity of the peak significantly increases with the concentration of the urea and glucose.

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