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Current time:0:00Total duration:5:58

Video transcript

diabetes mellitus is a group of disorders that's caused by improper function of the hormone insulin which is secreted by the pancreas now this results in dis regulation of blood glucose levels in the body specifically resulting in hyperglycemia or high blood sugar which is the hallmark of diabetes now since diabetes is a group of disorders this implies that there are multiple different conditions that can lead to diabetes mellitus which is true so let's break down diabetes into three major types type 1 type 2 and a third category which we'll just label as miscellaneous now before we dive into these three types of diabetes let's briefly review how the hormone insulin works in response to increasing blood glucose levels the pancreas produces and secretes a hormone known as insulin into the bloodstream and this insulin acts on cells throughout the body to remove the glucose from the bloodstream by either taking it up to use it for energy or to store it in the form of glycogen and as a result the blood glucose levels decrease and these decreased blood glucose levels then serve as a feedback mechanism to inhibit the pancreas from secreting more insulin so you can see that there are two major steps in this insulin pathway first insulin must be secreted by the pancreas in response to this increasing blood glucose level and second the cells throughout the body must respond to the insulin in order to carry out its metabolic functions in order to lower the glucose levels now this mechanism can be thought of as similar to that of a thermostat in an air conditioning within a home when the temperature goes up this is sensed by the thermostat which then sends an electrical signal to turn on the air conditioner which will then decrease the temperature and as the temperature goes down this will inhibit the thermostat from continuously keeping the air conditioner on and this mechanism here is going to become very important a minute as we differentiate the different types of diabetes mellitus so let's go through each of these types individually type 1 diabetes presents mostly during childhood and it's caused by a genetic predisposition plus some sort of environmental trigger exactly what this is isn't quite known but the combination of these two results in an autoimmune disorder in which the immune system attacks the beta cells of the pancreas to prevent them from producing insulin on the other hand type 2 diabetes typically although not always presents during adulthood and it's even more strongly associated with a genetic predisposition but in type 2 diabetes instead of this unknown trigger the genetic predisposition is accompanied with other predisposing conditions such as obesity or hypertension and this combination of factors results in an inability of these cells throughout the body to respond to insulin then although type 1 and type 2 diabetes are the most common causes of diabetes mellitus there are a couple other important causes of the disease and these include diabetes caused by medications known as drug-induced diabetes and drug induced diabetes most commonly occurs with a group of medications that are known as glucocorticoids which are steroid medications most frequently prescribed to decrease inflammation throughout the body such as with conditions like chronic asthma or Crohn's disease and the other miscellaneous cause of diabetes mellitus that's really important to mention is the diabetes that's associated with pregnancy known as gestational diabetes now let's tie this all together to receive a better understanding of how these different types of diabetes affect this underlying insulin pathway and result in diabetes mellitus in type 1 diabetes the this autoimmune attack on the beta cells of the pancreas prevent the production and secretion of insulin into the blood thus type 1 diabetes inhibits this first step in the insulin pathway and since it decreases the production of insulin it's referred to as an insulin deficiency however in type 2 diabetes as well as drug induced and gestational diabetes the pancreas continues to secrete insulin however it's the cells throughout the body that are unable to adequately respond to it so in a sense these mechanisms inhibit the second step in the insulin pathway and this is known as insulin resistance which can be thought of as a relative insulin deficiency so going back to this thermostat analogy if either the thermostat or the air conditioner is broken this system as a whole doesn't work the temperature inside the house is going to continue to rise similarly in diabetes mellitus it doesn't matter whether the underlying mechanism affects this first step such as with type 1 diabetes or the second step as with type 2 diabetes drug induced diabetes and gestational diabetes regardless there is going to be either an insulin deficiency or a relative insulin deficiency so this pathway will not work and the body won't be able to decrease glucose levels this results in an increased level of glucose which is known as hyperglycemia which as I mentioned at the beginning is the hallmark finding in diabetes mellitus