Why Do Patients With Diabetes Still Develop Chronic Complications?

In my last entry (June 8, 2009), I began a discussion about why, given how much we now know about preventing diabetes complications, patients still get retinopathy, neuropathy, nephropathy, and cardiovascular diseases.  I presented thumbnail sketches about 3 adolescents with type 1 diabetes whose medical histories ran the gamut from excellent to poor diabetes control.  Now I want to explore the subject in some detail.

What do we know about the relationship between the quality of diabetes care and the risks for developing chronic complications of the disease?

First, long-term studies such as the Diabetes Control and Complications trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) and the United Kingdom Prospective Diabetes Study(UKPDS) have shown clearly that development and progression of all major diabetes complications are strongly related to 3 factors- blood glucose control, blood pressure, and blood lipid levels.  So, simply put, the risk factors for diabetes complications are blood glucose levels, blood pressure levels, and cholesterol levels.  These risk factors are all controllable; hence, in 2009 it is possible to have diabetes, and with proper treatment, be at little or no risk of developing diabetes complications.  That is good news indeed.  Unfortunately, what is possible, is not happening for many people with diabetes; diabetes remains a leading cause of vision loss, nerve damage, kidney failure, and heart disease.

How can we tell if a person with diabetes is actually doing well in managing the condition?

It’s pretty easy for a physician to assess how well people with diabetes are doing in terms of the known risk factors for the development/progression of diabetes complications.  First, just measuring the blood pressure covers that risk factor.  Second, just measuring blood lipid levels covers another major risk factor.  Typically, physicians order a fasting lipid profile which measures blood cholesterol, tryglycerides, LDL-cholesterol (“bad” cholesterol), and HDL-cholesterol (“good” cholesterol).  Third, physicians can assess blood glucose levels by ordering  hemoglobin A1c (also called the A1c test).  The A1c test measures the amount of glucose attached to a person’s red blood cells, which is directly related to the average blood glucose level over the previous 3-4 months.  This test has been shown to be a powerful risk predictor for the development and progression of all diabetes complications (you might want to check out some of my previous entries that discuss this test in great detail).  In summary, all it takes is a stethoscope, a blood pressure cuff, and a bit of blood to assess/monitor risks for the development/progression of all diabetes complications.

Measuring risk vs. doing something about it

So, it’s quite easy to assess how well a person with diabetes is doing in terms of their risk for developing this or that diabetes conmplication.  It’s quite another thing to actually modify (i.e., decrease) a person’s risk factors once it has been determined that risks for this or that complication are increased.  For blood pressure and lipids, assuming the patient will remember to take a pill reliably (and can afford the medication), improving risks is easy.  For blood glucose control it’s not so simple since the solution generally requires that patients make changes in the way they manage their diabetes.  This is the area that I want to focus on in my next entry.

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