Carbohydrate metabolism is a fundamental biochemical process that ensures a constant supply of energy to living cells.The most important carbohydrate is glucose, which can be broken down via glycolysis, enter into the Kreb’s cycle and oxidative phosphorylation to generate ATP.Further important pathways in carbohydrate metabolism include the pentose phosphate pathway (conversion of hexose sugars into pentoses), glycogenesis (conversion of excess glucose into glycogen,stimulated by insulin), glycogenolysis (conversion of glycogen polymers into glucose, stimulated by glucagon) and gluconeogenesis (de novo glucose synthesis).Hormonal control and site of glucose regulation:Islets of Langerhans in the pancreas produce:1. alpha cells secrets glucagon2. beta cells secrets insulin3. delta cells somatostatinNORMAL BLOOD GLUCOSE LEVELS:Fasting blood glucose: 70-105 mg/dLMay rise to 130-160 mg/dL about 1 hr after a glucose load or after high carbohydrate meal (postprandial).After 2 hr, it drops back to normal fasting rangeHormones Affecting Blood Glucose Level :InsulinGlucagonEpinephrineGrowth hormoneAdreno-corticotropic hormone ACTHcortisolSomatostatinT3 &T4DIABETES MELLITUS :As per the WHO,diabetes mellitus (DM) is defined as a hetrogeneous metabolic disorder characterised by common feature of chronic hyperglycaemia with disturbance of carbohydrate, fat and protein metabolism.DM is a leading cause of morbidity and mortality world over. It is estimated that approximately 1% of population suffers from DM.CLASSIFICATION OF DIABETES MELLITUS :I.TYPE 1 DIABETES MELLITUS (10%) (earlier called Insulin-dependent, or juvenile-onset diabetes):Type IA DM: Immune-mediatedType IB DM: IdiopathicII.TYPE 2 DIABETES MELLITUS (80%) (earlier called non-insulin-dependent, or maturity.III. GESTATIONAL DIABETES MELLITUS-onset diabetes)IV. OTHER SPECIFIC TYPES OF DIABETES (10%)A. Genetic defect of β-cell function due to mutations in various enzymes (earlier called maturity-onset diabetes of the young or MODY) (e.g. hepatocyte nuclear transcription factor—HNF, glucokinase)B. Genetic defect in insulin action (e.g. type A insulin resistance)C. Diseases of exocrine pancreas (e.g. chronic pancreatitis, pancreatic tumours, post-pancreatectomy)D. Endocrinopathies (e.g. acromegaly, Cushing’s syndrome, pheochromocytoma)E. Drug- or chemical-induced (e.g. steroids, thyroid hormone, thiazides, β-blockers etc)