Pancreas is composite or heterocrine glands as they contain both endocrine and exocrine glandular tissues. Endocrine tissue is made up of small clusters of cells known as Islets of Langerhans which has two types of cells: Alpha cells that secrete glucagon and Beta cells that secrete insulin. Both these hormones together carry out Glucose metabolism. Glucagon carries out glycogenolysis and Insulin is responsible for cellular uptake of glucose. If insulin levels are not adequate the cellular uptake of glucose is affected or in other words transport of glucose from blood into cells is affected due to which blood glucose level rises. This is known as Diabetes mellitus. Polyuria (increase urination), Polydipsia (increased thirst) and polyphagia (increased hunger are symptoms of diabetes mellitus)