This morning several million people have taken a shot of insulin to control their blood sugar levels, as they did yesterday, and as they will do tomorrow. The insulin is delivered into the fatty tissue of the abdomen and is slowly absorbed into the blood stream. This method of taking insulin differs in a very important way from the means by which the pancreas supplies insulin to the body and this is the source of much trouble. Insulin courses through the blood and so we need to think for a moment about the path that blood takes as...

There are several forms of diabetes. The main forms are called Type 1 and Type 2. Here I will try to explain the underlying biology that leads to Type 1 diabetes. In the next post, I’ll tackle Type 2. Type 1 diabetes is very aggressive. Unlike Type 2, which can take a decade to develop, Type 1 can manifest in months. It is an autoimmune condition in which the insulin secreting cells of the pancreas (organized into structures called islets) are attacked by cells of the patient’s immune system. The reasons for this attack are...