Diabetic Macrovascular Damage

Macrovascular disease is damage due to large blood vessels.  There are basically three types of disease that are caused from large blood vessel damage.  They are blockages in the legs (peripheral arterial disease), blockages to the brain (stroke), and blockages in the heart heart arteries (heart attack).  Whereas microvascular damage tends to cause damage that makes life miserable, macrovascular damage results in conditions that cause the majority of deaths in diabetic patients.

All three of these conditions share similar features.  Unlike microvascular disease, strict blood sugar control by itself has not been shown to greatly decrease the risk of having these conditions.  A multi thronged approach is essential.  Controlling high blood pressure is critical.  Having both diabetes and high blood pressure more than doubles the risk of these conditions.  As such, the blood pressure goals in a diabetic are lower than for others.  Ideally, the blood pressure should not exceed 130/80.

Similar to hypertension, elevated cholesterol levels are more dangerous in diabetics as well.  Upper limits for the LDL (bad cholesterol) levels are 100 mg/dl.  This is the same goal as for those patients who already have established disease in their coronary (heart) arteries.  In fact, the risk of a heart attack in a diabetic patient is the same as for a patient who already has established heart disease.

Lastly, avoidance of cigarette smoking is critical in any patient but even more so in diabetics.  In regards to peripheral arterial disease (PAD), the only patients we see with this disease who are not diabetic are smokers.  Those with both conditions are at especially great risk.  PAD, in combination with neuropathy (see Diabetic Microvascular Damage) makes it extremely difficult to heal wounds, leading to sores and ulcers.  This may even lead to gangrene requiring amputation.

I hope that your understanding of what can go wrong with diabetes will be a stimulus to act now to prevent diabetes from progressing.  Consider the consequences above.  If a person with tendencies towards diabetes progresses to the point that their Hgb A1C is above 7.0% and requires medication, it will triggers a cascade of additional medicines.  Even at the beginning, a patient is likely to require a medicine for diabetes, an aspirin a day to prevent heart attack, a blood pressure medication and a cholesterol lowering medication.  At a minimum that is four medications.  Many patients require two, three or even four medications for the diabetes alone, three to five medicines for blood pressure and sometimes two medicines for cholesterol.  That is a lot of pills.  Not only will that be extremely expensive, there are possible side effects with all of those.  Don't wait till your doctor tells you have diabetes to take your health seriously. We all should be "on a diabetic diet."  We should all be exercising.  Now is the time to act.

Diabetic Microvascular Damage

Part of controlling diabetes is understanding the possible complications that comes from not keeping the blood sugars in check.  These complications all arise from damage to blood vessels due to elevated blood sugar levels.  Every organ system in the body can be affected.  Broadly speaking these complications are divided into two groups: macrovascular ones (large vessel) and microvascular ones (small vessel).  This week I'll be discussing the small vessel damage.

Microvascular Effects:
These changes have been shown to be closely linked with diabetic control.  Those who keep their hemoglobin A1C levels below 7.0%, do not for the most part develop these problems.  Let me discuss them in more detail.

Neuropathy: This is caused from damage to nerve fibers due to the diseased blood vessels that supply them.  The result is decreased feeling in the feet and poor wound healing.  A small pebble in the shoe which would be immediately taken out in a person with normal feeling may fester in a diabetic and cause a sore.  These sores can enlarge and get deeper.  If severe enough, infection can begin first in the skin (cellulitis) and later it may even reach the bones (osteomyelitis).  Bone infection is nearly impossible to cure with medications alone and can lead to amputation.  This often starts in the toes, continues in the forefoot and can lead to amputation above and below the knee.  Those with diabetes should inspect their feet each and every night prior to going to bed.  A tiny sore can be cured if caught early, evading the dreaded complications listed above.  Once a year, your physician should check the feeling in your foot using a simple filament test shown above.


Nephropathy: This is kidney damage.  In the United States diabetes is the number one reason for hemodialysis. Not only is hemodialysis inconvenient, it will greatly affect one's quality of life.  The chance of dying is five times higher in those who are on dialysis compared to those who are not.  Early diabetic kidney damage can be found by screening for protein in the urine.  In addition to keeping the blood sugars down, there are medications (ACE inhibitors and ARB's) that have been shown to slow the progression of diabetic kidney damage.  The urine should be checked at least once a year with your physician.

Retinopathy: The membrane in the back of the eye that allows us to absorb light and is responsible for vision is called the retina.  Blood vessel damage causes this important membrane to become thin and degenerate.  What is the number one cause for blindness in our country?  You guessed it, diabetes.  There are early changes that can be seen in the eye by an ophthalmologist.  Each diabetic should see an eye doctor once a year to be checked.  If damage is found, laser surgery can slow down this destructive process.  In the absence of good blood sugar control, though, it is usually a losing battle.


Arthropathy: This is a less well known complication of diabetes.  It is the slow destruction of the joints, often in the feet.  The delicate arch collapses and becomes deformed.  Together with neuropathy, dangerous pressure points develop that lead to ulcers and sores.  Specialized shoes can help off load these pressure points.  Once again, good blood sugar control will completely prevent this problems.

Your Diabetic Report Card

Everyone who has elevated blood sugars should be familiar with what the normal ranges of blood sugar are as well as the ranges for the hemoglobin A1C.  These are the markers that will tell you and your doctor what kind of control is being achieved and what your risk of future problems will be.

Let's start with your blood sugar.  In a normal individual a fasting blood sugar (defined as first thing in the morning prior to eating) should be less than 100 mg/dl.  In a diabetic, the goal is to keep that level below 120 mg/dl.  Certain medications used to treat diabetes can lower blood sugar too much, such as insulin.  A level below 70 mg/dl is too low.  Levels in the 40's or 50's can be dangerous.  Low blood sugar reactions can cause spikes in blood pressure, induce heart attacks or even seizures.

Blood sugar levels after eating in diabetic patients should be less than 150 mg/dl.  The best time to check the level is two hours after a meal.  If it is checked too soon, the level will be uninterpretable.  Diabetics tend to have levels that both spike too high after eating and go down too slowly.  Some diabetics may have normal readings in the morning but higher levels after eating.  If the sugar is checked only in the morning, that may not be picked up.  Others may have readings that are higher in the morning but normal after eating.  This is due to an abnormal release of glycogen (long chains of glucose) from the liver at night.  Both conditions are bad but may be treated in different ways.

Over the last twenty years a test has been developed and validated that has greatly enhanced our ability to both detect and treat diabetes.  It is called the hemoglobin A1C.  Whereas instant blood sugar readings tell us the state in the blood vessel at any given instant, the hemoglobin A1C (hgb A1C) gives us an overall view of how the blood sugars have been over the previous three months.  The test has been validated both as a marker of control and detection of diabetes.  Every diabetic should know what their number is.  The test is a measurement of sugar molecules that form on the surface of hemoglobin (the protein that carries oxygen in red blood cells).  The life span of this protein is 3-4 months.  These short chains of glucose are measured in percentages.  A normal person will have a hgb A1C of 4.5 to 5.9%.  Early diabetes starts at 6.0%.  Levels above 7.0% are dangerous and require medications.  Repeated studies have shown that maintaining a level under 7.0% greatly diminishes the chances of diabetic complications.  That said, the time to action is not when it reaches 7.0% and beyond but the moment that it is found to be 6.0% or higher.  This is the time when diabetes can be reversed through diet and exercise.

Know your numbers.  If you are seeing your physician for an annual physical examination, your blood sugar will be tested.  It is my practice to then check an hgb A1C in anyone whose fasting glucose is above 100 mg/dl.  If you wait till you have symptoms of diabetes to be evaluated, it is too late.  Excessive thirst, hunger, weight loss, blurred vision and the like will only occur after the sugars have gone above 250 mg/dl.  The time for action is now, don't wait to get checked.

Diabetes Prevention-Earning Your Calories

Michael Phelps at work

It should be pretty clear from the last two posts that sugar in the blood stream leads to the dangerous complications of diabetes.  Just as important as what is delivered to the blood vessels is how it leaves. The greatest source of energy demand is from the muscles.  If we don't use our muscles, they won't use up the sugar.  It is that plain and simple.  Conversely, when we actively use our muscles we turn into a blood sugar burning machine.  Well conditioned athletes use up a huge amount of sugar.  In the last Olympics, it was well documented that Michael Phelps, our gold medal, world record breaking swimmer, consumed around 9000 calories a day.  Most of those were in the form of carbohydrates.  That would put many of my diabetic patients in the hospital in a diabetic coma.  He had to consume that much to keep up with the amount of calories that his muscles were consuming due to his intense training.  However, I have witnessed many swim coaches who are over weight and at risk for diabetes.  The reason?  While they were actively training they developed a habit of heavy caloric intake which was not adequately scaled back when their training decreased.  The point is that exercise allows us to be able to eat more food.

One need not be an olympic swimmer to increase his ability to burn sugar.  Intensity matters but consistency is the key.  In the days when most of our population worked on farms, type II diabetes was not very common.  Today, where many of us work at computer screens or sitting down, the incidence is sky rocketing.  That is not a coincidence.  If you are not a construction worker or a farmer, you likely need more exercise.  I've discussed this in previous posts, but it does not matter what sort of activity you engage in as long as you are moving your muscles and getting your heart rate up.  The heart rate is an indicator that the muscles have used up their store of fuel and are calling out for a new delivery.  Whatever you choose to participate in, do it regularly.  It would be nice to be able to exercise just once a week for three hours and call it quits.  If we just ate once a week, I suppose that would work, but as long as we are putting fuel in the body, we need to keep the engine running.  I recently saw a patient in the office and I told him, "I'll make you a deal...you only have to exercise on the days that you eat."  The glimmer of hope that shone in his eyes as I started my sentence quickly turned to despair as he realized the point I was making.


I enjoy eating as much as anyone else.  I love ice cream.  I have been known to have a certain fondness for M&M's.  I realize that eating such items on a regular basis is a recipe for disaster.  Some years back to curb a nearly nightly habit of having ice cream, I put together my rules for eating.  I have followed these rules now for 15 years and I'll have to say that it has worked well for me.  During the week, I make sure and eat my five servings of fruits and vegetables a day.  I avoid all sweets, junk food, and yes, even ice cream.  On the weekends, I can eat anything I want, if and only if, I have exercised at least four days during the week.  I'll admit that in the beginning, I over did it on the weekends.  By Sunday, I would often feel bloated, lethargic and I often battled headaches.  Monday would be a relief.  I now no longer go crazy and feel much better for it.  It is nice to be able to sit down and have a milkshake without guilt.  I view it as a reward rather than a transgression.  Since I have burned it, I earned it!

Diabetes Prevention-The Right Fuel

Though there is not yet a cure for diabetes, type II diabetes is certainly preventable in most people.  Yes, some inherit a genetic tendency towards diabetes but that is not a guarantee of getting the disease.  As discussed in last week's post, the key to keeping diabetes at bay is to keep down the abdominal fat stores so that the pancreas does not become overworked.  Quite simply, if you are overweight you must burn more than you take in.  I realize that this is easier said than done.  I've discussed diet and exercise before but will readdress these topics with a specific emphasis on how diabetes is impacted.  I'll start with food intake and will discuss exercise next week.

First, let's talk about what is coming in.  If the goal is to minimize the amount of glucose (sugar) that reaches the blood vessels, sweets must be avoided. Table sugar is sucrose which chemically is composed of two glucose molecules stuck to each other.  It takes nearly no effort to split them in two.  Compare that to fructose, the molecule that fruit contains.  It is composed of one glucose molecule and another called galactose.  For the same amount of food ingested, there will be half as much sugar in whole fruit than in sweets.  In addition, fruit contains fiber, vitamins and other nutrients all of which are healthy.  The fiber makes the body work harder to digest the food and thus delays how quickly the nutrients reach the blood stream.  In addition to sweets, some foods have a much higher glycemic index than others.  Think of the glycemic index as how much sugar a given food delivers to the blood vessels.  Cereals are notoriously high, though the higher fiber cereals are much better than the others.  Bread, pasta and potatoes are also high glycemic foods.  Whole grains are always better than processed ones.  The bran and fiber in whole grains makes it harder to digest and will therefore deliver less sugar to the blood stream.  For more details about the glycemic index of specific foods, click here.

In addition to the types of food we eat, the amount eaten is just as important.  Our body uses sugar to meet its metabolic demands.  If too much glucose is delivered, it will get stored either in the liver as long chains called glycogen or be processed into fat stores.  If small amounts of food are eaten frequently, total calorie consumption will not need to be decreased in order to keep the weight stable.  In fact one of the worst things someone can do when trying to lose weight is to skip meals.  When going too long between meals, the body does not receive the nutrients that it needs so it enters starvation mode.  Signals are then sent throughout the body to turn down metabolism, lessening energy demand.  In addition, cortisol is released from the adrenal gland.  One of its effects is to decrease the sensitivity to insulin, thus raising blood sugar. It is best to have healthy food nearby during the day.  Just a few grapes or a bite or two of carrots will keep down hunger and maintain the metabolism.  Keep it small and keep it healthy.  

Lastly, eating a large meal late in the evening prior to going to bed is a recipe for disaster.  Very few of those calories will be metabolized.  The exception is if you chose to exercise in the evening before eating.  Exercise turns on a muscle enzyme called alcohol dehydrogenase.  It is quite good at burning up glucose.  It stays active in the muscles for 2-3 hours after exercising.  If you are going to have foods with a higher glycemic index, the time to eat them is during this window of opportunity after exercise.