Thursday, December 12, 2013

Why Don’t all People with Diabetes Need to Inject Insulin?

type 2 diabetesWhen many people hear diabetes, they often think it means injecting insulin several times a day.  Although that is true of type 1 diabetes, it is not always true of the much more common type of diabetes, type 2.  Type 2 diabetes is also called insulin resistance and is the most common form of diabetes.  People with type 2 are still producing insulin but a variety of their cells types lose the ability to properly respond to insulin signals.   Normally, when insulin binds to muscle or fat cells, the cells respond by actively taking glucose from the blood stream and use it for energy right away or store for later.  With the development of insulin resistance, the muscle and fat cells can’t “hear” insulin at normal “volume” so the pancreas response by producing ever increasing amounts of insulin to “turn up the volume” and allow cells to “hear”.  The liver cells also become resistant to insulin’s signal.  Normally, when insulin binds to liver cells, the liver cells stop producing and secreting glucose into the blood.  When liver cells become resistant to insulin’s signal they reduce glycogen synthesis and storage and instead push out too much glucose.   For a while, the pancreas will produce more and more insulin to try to push the muscle, fat and liver cells to bring down the blood glucose levels.  However, eventually it can’t keep up.  At that point, blood sugar can go to dangerously high levels, injuring blood vessels, eyes and kidneys and prevent normal wound healing.  This contributes to the cardiovascular disease that cause of 2/3 of deaths of all people with type 2 diabetes.  In the past, the only options to prevent this were weight loss, exercise and insulin injections.  Now we have some other options.

There are several medications that can be used to improve cells ability to “hear” insulin.  The most common is Metformin which mostly acts on the liver, making the cells more responsive to insulin so they lower their production and secretion of glucose into the blood.  Metformin has a track record at preventing cardiovascular complications of diabetes as well as helping to reduce blood levels of LDL (bad form of cholesterol) and triglycerides.  There are generic forms of Metformin so it is available to patients at a lower cost.  However, Metformin has very little effect on insulin resistance of muscle cells – it can’t help muscle cells pull glucose out of the blood stream. 

Another group of drugs, thiazolidinediones (TZDs), acts by making muscle and fat cells better respond to insulin.  Examples are Avandia (Rosiglitazon) and Actos (Pioglitazone).   Because the muscles and fat cells respond better to insulin, they pull more glucose from the blood for use for immediate energy or storage and blood glucose levels go down.  For many years, there was a big concern that TZDs like Avandia were causing people with diabetes to have more heart attacks.  Because of that, the FDA restricted the use of Avandia and its related drugs to only a few people.  However, recently, the FDA announced that a multiple year study in Europe showed that drugs like Avandia cause no more heart attacks than Metformin.  People who take drugs like Avandia will still need to be monitored for heart problems, but doctors won’t have to jump through complicated administrative hoops to prescribe the drugs.  Currently there are no generic forms of Avandia but the patent expired in 2012.  Soon generic Rosiglitazone will become available and people with diabetes will have a lower cost option. An application by TEVA Pharmaceutics USA was approved Jan 25, 2013.

There are also a number of different medications that help the pancreas produce more insulin and others that reduce nutrients being absorbed from our food.  So all together, diet, exercise and medications mean that people with insulin resistance do not need to inject themselves with insulin.

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