Insulin is a secretary heterodimer polypeptide hormone consisting of alpha and beta chains of 21 and 30 amino acids respectively bound by disulphide bonds. Insulin is synthesized in the Beta cells of islets of Langerhans found in Pancreas tissue and released into blood stream, which acts on various cells of different tissues. Insulin binds with Insulin receptors, a class of surface receptor tyrosine kinase family and activates the receptor by auto-phosphorylation. The activated Insulin receptor further phosphorylates down stream target Insulin receptor substrate (IRS) family members, which finally leads to the formation of a secondary messenger molecule, Ptd (3, 4, 5) P3 (phosphatidy - 3, 4, 5 - triphosphate). Ptd (3, 4, 5) P3 triggers AKT (PKB) kinase phosphorylation. Activation of AKT kinase leads to the phosphorylation of GSK3 (Glycogen synthase kinase 3). Phophorylation of GSK3 makes the enzyme inactive and there by decreases the phosphorylation of its substrate Glycogen synthase, a rate limiting enzyme in the glycogen synthesis. Phosphorylation of Glycogen synthase by GSK3 leads to the inactivation of the Glycogen synthase, which leads to inhibition of glycogen synthesis. Hence the GSK3 inactivation (phosphorylation) by AKT results in the activation of Glycogen synthase, thereby increasing the conversion of glucose into glycogen resulting in the decrease blood sugar level.
Insulin not only reduces blood sugar by increasing Glycogen synthesis, inhibits the synthesis of glucose from glycogen in liver. Further Insulin triggers uptake of glucose from blood into cells via GLUT4 (Glucose transporter type 4) gene. Insulin also inhibits protein degradation and stimulates amino acids up take into cells promoting protein synthesis. With the combined effect of glucose uptake, glycogenesis and inhibiting glycogenolysis, the blood sugar is maintained in the body by Insulin. Any variations in the insulin pathway, results in condition known as Diabetes, where it results in defective uptake of glucose or storage of glucose are observed.
Diabetes is a condition, where the person's blood sugar level is always higher. The inability of body to synthesis Insulin is known as Type 1 Diabetes (Insulin Dependent Diabetes Mellitus), while in Type 2 Diabetes (Non Insulin Dependent Diabetes Mellitus), the body becomes resistance to insulin. Both Type 1 and Type 2 Diabetes can't be cured completely but can be controlled with proper medication, controlled diet and exercise. Diabetes occurs due to changes in life style and the primary reasons for Diabetes is genetics/ hereditary of the individual. There are several genes found to be associated with Diabetes such as HNF4A, COUPTFII, INS, INSR, IDDM1, PPARgamma, ABCC8, etc. Patients with Diabetes are suggested to consume foods that are less rich in carbohydrate and to eat small serves of food in short intervals. This food habit will help the patient to have the blood sugar level in the acceptable range. Diabetes results not only in the defective uptake of glucose but also in the conversion of glycogen to glucose, long gap between the food serve drastically decreases the blood sugar and hence will lead to fatigue in the patients. Diabetes patients are suggested to take cereals like wheat or ragi, etc., instead of rice as rice is rich in carbohydrates. The body readily converts glucose from the carbohydrates of rice, thereby increasing the blood sugar level immediately after food intake.
The symptoms of Diabetes are frequent urination, increased thirst and hunger with fatigue with normal physiological activities. The prolonged Diabetes without proper treatment will lead to damage of vision, increased risk of cardiovascular diseases, might lead to damages of blood capillaries, damage to kidney and nervous system. The cells of diabetic patient have very slow healing capacity, hence small wound if not properly monitored might lead to ulcers which requires amputation to save patient's life.
Diabetes is diagnosed by checking blood sugar level at different time points to come to an accurate result. Fasting sugar level is done in the early morning with empty stomach and Non fasting Glucose test done after two hours after consumption of food. Fasting glucose of sugar level >=126 mg/ml and >=200 mg/ml of sugar in 2 hour glucose test indicates a Diabetes condition. Diabetes itself is not a killer disease but if neglected will lead to complication involving many organs failure culminating in death. Diabetic patient with proper medication, life style and balanced diet can lead a normal life.
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