An accurate assessment of long term blood glucose control in diabetes is determined by the measurement of A1C, previously known as hemoglobin A1C or HbA1c, and is now recognized by the American Diabetes Association as a reliable tool for the diagnosis of diabetes. Blood glucose attaches itself to the hemoglobin protein of red blood cells by a permanent process called glycosylation. This allows your doctor to have an overall picture of blood glucose control for the past 3 to 4 months, which is the average lifespan of a red blood cell. Chronic high blood glucose, as identified by A1C, is a risk factor for a number of complications that can range from the mild to the severe.
Macrovascular Complications
Poorly controlled diabetes directly affects the overall health of the cardiovascular system. The lining of blood vessels, called the endothelium, produces a host of vasoprotective substances of which Nitric Oxide is the most well known. Hyperglycemia reduces the production of Nitric Oxide and the diabetic endothelium may be dysfunctional for several hours after eating. This promotes vascular inflammation, enhanced thrombosis and increased artery stiffness. Macrovascular complications include coronary artery disease, cerebrovascular disease, and peripheral vascular disease. This places the poorly controlled diabetic at increased risk for heart attack, heart failure, stroke and limb amputations due to gangrene.
Microvascular Complications
Chronically poor blood sugar will affect the health of the eyes, nerves, and kidneys. Blood sugar naturally diffuses through the lens capsule of the eye where it can attach to lens proteins leading to cataracts. Diabetes is also associated with damage to the microvascular layer that nourishes the retina, the light sensitive tissue which connects to the ocular nerve. The damage can be relatively mild where there are minimal amounts of leakage from the blood vessels that nourish the retina, to the most severe where there is new vascular growth.
High blood pressure and increases in glucagon and growth hormone from erratic blood glucose fluctuations all put stress on the glomerulus, which is an integral part of the kidney. Eventually there is a hardening of the glomerulus with resulting destruction of individual nephrons, the sight of filtration in the kidney. As more nephrons are destroyed, the workload for the remaining nephrons increases which adds to the overall stress on the kidney. If left untreated, end stage renal disease will result.
Elevated A1C due to uncontrolled blood sugars impact the nervous system over a wide spectrum that range from the relatively mild such as erectile dysfunction, to the more challenging such as sensory pain and exercise intolerance, which greatly impacts and individual's ability to perform activities of daily living and overall quality of life.
Reducing Your Risk
Improved metabolic control is the most significant step an individual can take to avoiding the complications associated with diabetes. The classic complications prevention trials, the DCCT and UKPDS, both showed that chronic complications of diabetes can be significantly reduced and managed through improved A1C. The management of cholesterol and triglycerides, commonly known as lipids, along with improved blood pressure are central to the successful long term management of diabetes and its related complications. The American Diabetes Association recommends that tight control over A1C, blood pressure, and blood lipids be aggressively pursued through lifestyle modifications and pharmacological therapies if needed.
References
- The Art and Science of Diabetes Self-Management Education; American Association of Diabetes Educators; 2006
- Diabetes Care; Nephropathy in Diabetes; American Diabetes Association; 2004
- Diabetes Care; Diabetic Neuropathies; Andrew J.M. Boulton et al.; 2005
- Diabetes Care; Retinopathy in Diabetes; Donald S. Fong et al.; 2004
- Diabetes Care; Summary of Revisions for the 2010 Clinical Practice Recommendations; American Diabetes Association; 2010
