The word diabetes is related to excess urination or polyuria. In physiology, we study two types of diabetes. One is diabetes mellitus, and other is diabetes insipidus. Both of the diseases are way different from each other due their cause and origin etc., but they have one thing in common: excess urination. Diabetes mellitus is a most common type of diabetes; it is characterized by excess glucose level in the blood that is followed by excess urination. And, diabetes insipidus is the disorder characterized by the excess urination due to function instability of ADH or lack of ADH, in this excess water is lost from the body which results in many serious conditions like dehydration, etc. The main difference in between diabetes mellitus and diabetes insipidus is the hormone. In diabetes mellitus Insulin is involved, whereas in diabetes insipidus ADH is involved.
What is Diabetes Mellitus?
Diabetes means excess urination and Mellitus means honey. Diabetes mellitus is the most common disorder seen around. This disorder is characterized by excess glucose in the blood which leads to polyurea. Normal blood glucose level varies from 70-110mg/dl. After intake of food, blood glucose level rise which results in the secretion of a specific hormone named as Insulin. Insulin is the only hormone that reduces blood glucose level. As insulin is secreted from beta cells of the pancreas, it shows its action. It is bound to the receptors on the cell surface and produces the second messenger inside the cell mostly calmodulin, and this activates GLUT-4 in the cell which helps in the absorption or uptake of glucose by the cells. In this way, glucose in blood moves inside the cells and blood glucose level comes to normal. Moreover, insulin promotes the formation of glycogen (glycogenesis) which also reduces blood glucose. But in diabetes mellitus, blood glucose level do not decrease. By the cause diabetes mellitus is divided into two types: Diabetes mellitus type 1 or IDDM: In type 1, there is a lackness of insulin hormone. This is due to dysfunctioning of beta cells of the pancreas; beta cells fail to produce insulin due to which blood glucose level increases enormously and can not be decreased. It is also called IDDM or insulin dependent diabetes mellitus. In this patient can be given insulin externally. Diabetes mellitus type 2 or IIDM: in type 2, insulin is sufficient in the body, but cells develop insulin resistance due to which they do not show any response to insulin. Now insulin can not perform its action because cells do not show any effect of insulin. Thus blood glucose can not be reduced. In this external insulin is not given, the patients use only oral drugs. Diabetes mellitus is a serious problem that can lead to many disabilities of the body and may cause death. The patient became weak day by day; he feels pain in the body, and he also feels hungry every time because glucose is lost in urination.
What is Diabetes Insipidus?
Diabetes insipidus is a rare form of diabetes; it is characterized by the excess urination due to lack of pituitary hormone ADH (vasopressin), which act on kidney and regulate excretion of water from the body. In diabetes insipidus, pituitary fails to secrete ADH in sufficient amount or stops it completely. Due to which excess water is lost from the body. ADH hormone has a vital role in our body hemostasis. ADH when secreted in blood act on the kidney. First, distal convoluted tubule and collecting duct of nephrons are impermeable to water. ADH makes them permeable so that water can be reabsorbed from here. In this way, ADH prevents excess loss of water. ADH secretion increases when there is a low concentration of water in the body, so it retains the water. But in diabetes insipidus, ADH is not secreted by the pituitary. Now the distal convoluted tubule and collecting duct of nephrons are impermeable to water so no water can be reabsorbed. Water is moved to the urinary bladder and lost in urine. When excess water is lost, it results in decreased water concentration in the body which can result in serious problems. The first problem is dehydration that can even lead to death or shock if not compensated within the time. Due to low water content, the patient is forced to drink more and more water, and this water is continuously lost in urine resulting in the condition called polyurea.
Diabetes Mellitus vs. Diabetes Insipidus
- In diabetes mellitus, blood glucose level is high, whereas in diabetes insipidus, the glucose level is normal but excess water is lost.
- Diabetes mellitus is related to a hormone called insulin, while diabetes insipidus is related to hormone ADH.
- In diabetes mellitus, a gland that is involved is pancreas and contrary to that in diabetes insipidus, the pituitary gland is involved.
- Diabetes mellitus is more common in types of diabetes while diabetes insipidus is less seen.
- In diabetes mellitus, patient feel hungry due to loss of glucose in urine, on the other hand, in diabetes insipidus, patient feels thirsty due to loss of excess water.