Jaslok Hospital and Research Centre,
Diabetes is so widespread that there would scarcely be a person who does not know someone who has diabetes. Often, that person may be a family member.
You may well ask, " What does that have to do with me…why should I know about diabetes?"
Superficially, this would seem to be good question. But think about it.
If you have friends or family members who have to live all their lives with diabetes, they will always need support and understanding about their disorder. Would you not like to give them that support and encouragement so that they are able to manage their diabetes and live as normal and healthy a life as possible without feeling like a pariah?
Ask them, and you will realize how much they would appreciate your being there to help them. But how will you help unless you understand diabetes and know what they are going through!
More importantly, if you have a family member who has diabetes, there are good chances that you too will get diabetes. Would you like to know what your chances are? Click here.
Even if you find that your chances are just 25%, you could shrug it off by saying that that is just one in four. But how do you know you would not be that one in four!
Today, we know that we can try and avoid diabetes, especially the common Type 2 diabetes ( which is around 98% of all diabetes seen here) by taking various measures such as lifestyle changes etc. But all these changes will only make sense if you understand why you be making the changes and trying to avoid diabetes.
You cross a road because you know why you want to go across. If you did not why, then why would you cross the road? Similarly, if you accept that you will make some changes in your lifestyle ( and too for a prolonged period of your life), do you not want to know the reason why you are making the changes.
You would say to avoid diabetes…….but do you know what is diabetes!
So understanding diabetes, even if you do not have it, is important. Not only will you be able to offer help and understanding to your friends and family members having diabetes, which in itself can be invaluable to them, but as importantly, you may just be helping yourself avoid diabetes!
The best way to avoid something, is to know about it.
Many of you may have seen the famous film, "Patton" in which there is scene where General Patton defeats Rommel in tank warfare in the Arabian deserts. When Patton has won over Rommel, long considered the ultimate master of desert warfare, so much so that he was nicknamed the "desert rat", Patton waves a book on tank warfare on the desert written by Rommel and shouts, " I mastered your own book, you…..!" Patton had defeated Rommel by having knowledge about desert tank warfare by learning from the master, and using this knowledge he was able to defeat Germans.
To put it very simply, diabetes mellitus is a chronic and currently incurable condition in which too much glucose (sugar) is present in the blood.
Since diabetes is a disease that affects your body's ability to use glucose, let's start by looking at what glucose is and how your body controls it.
Glucose is a simple sugar, which is normally necessary to provide energy to the cells in your body. The various cells in your body take up the glucose which is in the blood and break it down using various biochemical pathways into "energy". Whilst in the absence of glucose, many cells and organs can use other substitutes for a while, important cells such as those of the brain, the red blood cells and the those of kidneys can only use glucose and nothing else.
When you eat food, the carbohydrates in the food, and remember most of the diet is full of carbohydrates (starch, in popular parlance), gets broken down in the intestines into simple sugars such as glucose which are then absorbed into the bloodstream and get distributed all over the body for it to be used. When you have something with simple sugars, the glucose gets absorbed that much faster!
But we do not eat continuosly. So our body has a mechanism which closely regulates the level of glucose in the bloodstream so that the cells of the body can get their required supply at all times. Unless this is done, your cells would have too much glucose right after a meal and starve in between meals and overnight !
So, when you have an oversupply of glucose, your body stores the excess in the liver and muscles by making glycogen, long chains of glucose. When glucose is in short supply, your body mobilizes glucose from stored glycogen and/or stimulates you to eat food.
The key is to maintain a constant blood-glucose level. Think of this as some sort of a "depot" where you store excess materials for later use. So how does the body fine tune this mechanism by which a normal amount of glucose is available for use by the body at all times?
To maintain a constant blood-glucose level, your body relies on two hormones produced in the pancreas that have opposite actions: insulin and glucagon. Although things are not that simple and many other mechanisms do come into play, it will suffice for our purposes to understand the basic role played by these two hormones.
The pancreas is composed of two main parts, the exocrine part and the endocrine pancreas. The exocrine part secretes substances into the intestinal tract which help in digestion of the eaten food. These include lipase, which helps to digest fat, and amylase that helps to digest starchy foods. It also releases 'bicarbonate of soda' to neutralise any stomach acid that may otherwise damage the lining of the gut. The exocrine pancreas is directly connected to the intestinal tract through the pancreatic duct as seen below.
But we are basically concerned in diabetes with the endocrine pancreas which is the source of insulin, glucagon and other hormones, secreted directly into the bloodstream.
The pancreas is full of tiny cluster of cells called the Islets of Langerhans, which surround the cells of the "exocrine" pancreas.
The islet of Langerhans contains many types of cells
The pancreas has many islets that contain insulin-producing beta cells and glucagon-producing alpha cells.
Insulin is made and secreted by the beta cells of the pancreatic islets, small islands of endocrine cells in the pancreas. In the beta cell, the insulin is made and stored as a precursor called proinsulin. When the B cell is appropriately stimulated, insulin is secreted from the cell by exocytosis and diffuses into islet capillary blood. C peptide is also secreted into blood, but has no known biological activity.
Insulin is a protein hormone that contains 51 amino acids After a meal the digestive system breaks some food down into glucose. The blood carries the glucose or sugar throughout the body, causing blood glucose levels to rise.
In response to this rise the hormone insulin is released into the bloodstream to signal the body tissues to metabolize or burn the glucose for fuel, causing blood glucose levels to return to normal.
Glucose the body doesn't use right away goes to the liver, muscle or fat for storage. Under normal circumstances the hormone insulin, which is made by the pancreas, carefully regulates how much glucose is in the blood. Insulin stimulates cells to absorb enough glucose from the blood for the energy, or fuel, that they need. Insulin also stimulates the liver to absorb and store any glucose that's left over. After a meal the amount of glucose in the blood rises, and this triggers the release of insulin.
When blood glucose levels fall, during exercise for example, insulin levels fall too. A second hormone manufactured by the pancreas is called glucagon. It stimulates the liver to release glucose when it's needed, and this raises the level of glucose in the blood.
Insulin is required by almost all of the body's cells but its major targets are liver cells, fat cells and muscle cells. For these cells, insulin does the following:
Insulin and glucagon have opposite effects on liver and other tissues for controlling blood-glucose levels So, what happens when you do not eat? In times of fasting, or when there has been a long time after a meal and the blood levels of glucose drop significantly, your pancreas releases glucagon so that your body can produce glucose. Glucagon is another protein hormone that is made and secreted by the alpha cells of the pancreatic islets.
Glucagon acts on the same cells as insulin, but has the opposite effects:
In contrast to insulin, glucagon mobilizes glucose from stores inside your body and increases the concentrations of glucose in the bloodstream otherwise, your blood glucose would fall to dangerously low levels.
Normally, the levels of insulin and glucagon are counter-balanced in the bloodstream. For example, just after you eat a meal, your body is ready to receive the glucose, fatty acids and amino acids absorbed from the food. The presence of these substances in the intestine stimulates the pancreatic beta cells to release insulin into the blood and inhibit the pancreatic alpha cells from secreting glucagon. The levels of insulin in the blood begin to rise and act on cells (particularly liver, fat and muscle) to absorb the incoming molecules of glucose, fatty acids and amino acids. This action of insulin prevents the blood-glucose concentration (as well as the concentrations of fatty acids and amino acids) from substantially increasing in the bloodstream. In this way, your body maintains a steady blood-glucose concentration in particular.
Thus, one can say that insulin is the key that opens the door to let glucose into the cells.
In contrast, when you are between meals or sleeping, your body is essentially starving. Your cells need supplies of glucose from the blood in order to keep going. During these times, slight drops in blood-sugar levels stimulate glucagon secretion from the pancreatic alpha cells and inhibit insulin secretion from the beta cells. Blood-glucagon levels rise. Glucagon acts on liver, muscle and kidney tissue to mobilize glucose from glycogen or to make glucose that gets released into the blood. This action prevents the blood-glucose concentration from falling drastically.
As you can see, it is this "Balance" between insulin and glucagon secretions throughout the day and night which helps to keep your blood-glucose concentration within normal bounds.
In diabetes, this balance gets tilted and this leads to a rise in the blood glucose levels to what we call "diabetic" values. This arises because the body cannot use the glucose properly, either because of a lack of the hormone insulin or because the insulin available does not work effectively. Not only is excess sugar found in the blood but it may appear in the urine too.
In people with diabetes, the pancreas either produces little or no insulin, or the cells do not respond appropriately to the insulin that is produced. Glucose builds up in the blood, overflows into the urine, and passes out of the body. Thus, the body loses its main source of fuel even though the blood contains large amounts of glucose. Diabetes mellitus is a disease in which the cells are starving in a sea of glucose.
As you are aware, there are two main types of diabetes:
In Type 1, the body is unable to produce any insulin. Type 1 diabetes is an autoimmune disease. An autoimmune disease results when the body's system for fighting infection (the immune system) turns against a part of the body. In diabetes, the immune system attacks the insulin-producing beta cells in the pancreas and destroys them. The pancreas then produces little or no insulin.
At present, scientists do not know exactly what causes the body's immune system to attack the beta cells, but they believe that autoimmune, genetic, and environmental factors, possibly viruses, are involved. In a Type 1 diabetic, the beta cells produce little or no human insulin. When this happens the blood sugar level begins to rise to a dangerous level.
Type 1 diabetes develops most often in children and young adults, but the disorder can appear at any age. Symptoms of type 1 diabetes usually develop over a short period, although beta cell destruction can begin years earlier.
Symptoms include increased thirst and urination, constant hunger, weight loss, blurred vision, and extreme fatigue. If not diagnosed and treated with insulin, a person can lapse into a life-threatening diabetic coma, also known as diabetic ketoacidosis.
In Type 2 diabetes, not enough insulin is produced or the insulin that is made does not work properly.
The most common form of diabetes is type 2 diabetes. Type 2 diabetes is often part of a metabolic syndrome that includes obesity, elevated blood pressure, and high levels of blood lipids.
When type 2 diabetes is diagnosed, the pancreas is usually producing enough insulin, but, for unknown reasons, the body cannot use the insulin effectively, a condition called insulin resistance. After several years, insulin production decreases. The result is the same as for type 1 diabetes--glucose builds up in the blood and the body cannot make efficient use of its main source of fuel.
The following is another way of understanding Type 2 diabetes.
Type 2 diabetes can be strongly triggered by a person's lifestyle, weight, exercise level on a strong genetic background
For a quick interactive look at the basics of diabetes, Click here