Quitting Smoking, Improving Blood Sugar Control Result in Rapid Reduction in Kidney Disease Risk
BOSTON — January, 2002 — A study from Joslin's Section on Genetics and Epidemiology shows that patients with type 1 diabetes can quickly begin to reduce their risk of microalbuminuria (the earliest sign of kidney disease) if they quit smoking and improve their blood sugar control. In fact, the researchers state, smoking in patients with type 1 diabetes appears to be an extremely important risk factor for microalbuminuria, and the effect of high blood sugar combined with smoking on the risk of developing microalbuminuria is greater than the sum of their separate effects.
The study was completed in 943 patients from Joslin and reported in the December issue of the journal Diabetes.
Diabetes is the most common cause of kidney failure, accounting for more than 40 percent of new cases. About 16 million people in the United States have either type 1 or type 2 diabetes, and about 100,000 people have kidney failure as a result of diabetes.
Andrzej S. Krolewski, MD, Ph.D., and colleagues at Joslin identified 943 patients with type 1 diabetes who did not have any signs of microalbuminuria over a two-year period, and then followed them for an additional 4 years. During that additional time period, 109 of the participants developed microalbuminuria, which is small amounts of protein in the urine and an early sign of kidney deterioration.
Analyzing the results, the researchers showed that the incidence of microalbuminuria rises almost imperceptibly as hemoglobin A1c results rise to 8%. Above that level, microalbuminuria and the risk of kidney problems that it suggests rise steeply. "High blood sugar did not seem to have a cumulative effect, however," says Dr. Krolewski. "If the patient had poor blood sugar control in the past, but then improved, the risk of kidney complications declined."
Quitting smoking should also lead to a greatly decreased risk of developing kidney complications within a short period of time. Dr. Krolewski adds, "This is different from other diseases associated with smoking - a smoker has to wait about 10 years after quitting before their risk of cancer is significantly reduced, for example."
Patients who smoked and had poor blood sugar control were at greatest risk for developing kidney complications, and their risk was greater than the sum of the risk from either smoking or poor blood sugar control.
These findings offer a great incentive for patients with type 1 diabetes to quit smoking and improve their blood sugar control. While the study was done only in patients with type 1 diabetes, Dr. Krolewski speculates that people with type 2 diabetes might likely benefit in similar fashion from quitting smoking and improving their blood sugar control. Other studies have shown the positive benefits of improved blood sugar control in preventing eye and heart disease in both type 1 and type 2 diabetes patients, he notes.
