Focus on Diabetes Health: Types of diabetes

By: Michael K. Laidlaw, MD
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Case: HM is a 38-year-old man who has had three weeks of frequent urination, excessive thirst and weight loss of 15 pounds. He is seen in the emergency room and told that his blood glucose is 440. Does this man have diabetes and, if so, what type?

Diabetes may be simply defined as a high blood glucose (commonly called sugar) level. A blood glucose of over 200 when checked at any time of the day (and repeated for verification) is diabetes. The man above has typical symptoms of uncontrolled diabetes and a blood glucose of well over 200. Now that we know he has diabetes, is it type 1 or type 2? Or could it be some other type?


Type 1 diabetes

Type 1 diabetes is somewhat easier to understand, so let's begin here. Recall that glucose is a type of sugar found in your blood. It comes from foods that we ingest, particularly carbohydrates such as bread, rice, pasta and potatoes. These foods are broken down by the intestines into glucose which is then passed into the blood. Ultimately, the glucose needs to make its way into muscle, nerves and all of the other cells of the body to use for energy or be stored. But the glucose doesn't simply wander over to the cell and slip inside. It needs to be invited inside. Insulin makes this happen.

Insulin is a hormone created by an organ called the pancreas that lies deep in the upper abdomen or belly area. The cells of the pancreas can sense changes of glucose levels in the blood stream. After a meal, when glucose levels start to rise, these cells sense the change and release insulin. This hormone then travels to the cells and provides a signal for each cell to transport the glucose inside. In this way the glucose digested after eating a meal is distributed to every cell of the body.

But what would happen if the pancreas stopped making insulin? What would happen to the glucose then? As you might suspect, glucose would not be able to enter the cells. Therefore, blood glucose levels rise and diabetes ensues. This is essentially what happens with type 1 diabetes. In this disease the pancreas makes very little or no insulin, therefore the blood glucose levels become very high.

But what causes the pancreas to stop making insulin? Type 1 diabetes is referred to as an autoimmune disease. What this means is that the body's immune system, which should be fighting bacteria, viruses and other bad guys, is instead attacking its own organs. In the case of type 1 diabetes, the immune system attacks the cells of the pancreas that make insulin. Exactly why this happens is unknown, but various environmental, genetic and even infectious causes have been postulated.

So does this patient have type 1 diabetes? Stay tuned for Part Two of this series to find out more.


Michael K. Laidlaw, MD, is a Rocklin physician specializing in endocrinology, diabetes and metabolism.