In addition to the two types of diabetes mellitus that we looked at in this column last week (T1DM and T2DM), there is also gestational diabetes and Pre-Diabetes.

In addition to the two types of diabetes mellitus that we looked at in this column last week (T1DM and T2DM), there is also gestational diabetes and Pre-Diabetes. It is estimated that more than 30 million people in the US have diabetes; 90% of these have T2DM, and probably 25% or more of these do not know that they have the disease. Gestational diabetes is similar to T2DM, in that it is due to insulin resistance, but it is found in women that do not have diabetes before pregnancy. Many of these women do go on to T2DM later in life.

Insulin resistance is the root problem in T2DM, and we learned last time that this is a "failure to communicate." It is a little like having a car with a sticky or sluggish accelerator pedal. If your car's accelerator pedal does not move freely you won't be able to properly communicate how much gas you want to put into your engine, and your car will not accelerate smoothly. Sometimes there will be not enough fuel and sometimes too much. In a similar way it is not uncommon for the first symptom of insulin resistance to be blood sugar that is too low, a condition known as hypoglycemia, before the blood sugar becomes too high.

Diabetes damages the body in many ways. It is the seventh leading cause of death in this country and the number one cause of kidney failure and lower-limb amputation as well as the leading cause of adult blindness. It greatly increases the chance of heart attack and stroke, impairs the body's ability to fight infection or repair itself and it damages nerves, especially the ones in the legs. Most of these effects are related to the effects of sustained high sugar levels.

These high levels cause changes in the molecular structure of many of the proteins etc. that are necessary for life. One example of such a chemical change is known as hemoglobin A1c (HgbA1c) which is used to estimate the average blood sugar over the last three months. Very simply, hemoglobin is a large protein molecule that is prone to chemical change in the presence of sugar in the blood. In a very literal sense a sugar molecule gets stuck onto a hemoglobin molecule. The percentage of the hemoglobin molecules that have been changed in this way is thus dependent on the level of sugar and the length of time exposed. The more sugar, the more rapid the change and the higher the percentage of changed hemoglobin molecules. Since hemoglobin in a red blood cell (RBC) is manufactured at the same time that the RBC is created, and the life of each RBC is usually about three months, normally some of the hemoglobin molecules (about 4 to 6%) in a sample of blood will have this sugar stuck on. Finding HgbA1c above 6.5% is diagnostic of diabetes. Red blood cells and hemoglobin molecules have a relatively short life, and the sugar does not materially affect their biological usefulness.

On the other hand, nerves and blood vessels as well as their constituent molecules are expected to last for decades, so these are where we see the most damaging effects. The large vessels are affected, leading to loss of circulation to the legs and feet, and the small vessels are affected leading to blindness. There are direct effects on the function of nerves, and nerves are also affected due to damage done to the small vessels that are their blood supply. This damage to nerves causes some people to experience severe pain in their feet, and causes some people to lose much of the sensation in their feet -- and some people get both of these problems at once-- the longer the nerve, the more it is affected, hence the problem is worst in the feet. This lack of sensation makes them prone to getting sores that go unrecognized until they are infected.

On top of that, the body's white blood cells are very ineffective at fighting infection when the blood sugar is over 200. Thus high sugar levels over a prolonged period of time results in a perfect storm of injury, infection and ultimately amputation. The kidney, heart and brain are affected by both the small vessel and large vessel damage. Return here next week for the final installment on diabetes, or go to https://www.niddk.nih.gov/health-information/diabetes for more information.

Dr. Bundrant is the chief of staff at Ballinger Memorial Hospital and a member of the the Health and Wellness Coalition of Runnels County. The group will meet March 8 in the conference room adjacent to Keel Drug to discuss emergency preparedness, planning and coordination in Runnels County.