[Weekly Health] Diabetic but still smoking?... Risk of complications drops after quitting smoking for 8 years

(Seoul = Yonhap News) Reporter Kim Gil-won = It is a well-known fact that when diabetic patients smoke, the risk of cardiovascular diseases such as myocardial infarction and stroke increases. For this reason, for diabetic patients, quitting smoking is an important lifestyle rule that is emphasized as much as blood sugar management.

However, it was relatively unclear how much the risk of 'microvascular complications' that damage the kidneys, eyes, and nerves is actually reduced when a diabetic patient quits smoking, and how long it takes to quit smoking for the effect to be seen.

A domestic research team has published research results that can answer these questions.

According to the latest issue of the international academic journal 'JAMA Network Open', a joint research team from the Department of Preventive Medicine and the Department of Occupational and Environmental Medicine at Kyung Hee University School of Medicine conducted follow-up observations for an average of 9 years on 209,698 adults who were first diagnosed with type 2 diabetes between 2003 and 2013 and whose smoking was repeatedly confirmed through health checkups, and found that the longer the period of smoking cessation, the lower the risk of diabetic microvascular complications.

The average age of the study subjects was 57.2 years old. By smoking status, there were 162,861 non-smokers, 11,848 quitters, and 34,989 continuous smokers. Smokers who quit smoking were subdivided into those who quit smoking for less than 2 years, 2 to 3 years, 4 to 5 years, 6 to 7 years, and more than 8 years.

As a result of the analysis, there was a clear tendency for the risk of diabetic microvascular complications to decrease as the smoking cessation period increased.

Based on continuous smokers, the overall risk of microvascular complications was 19% lower in people who quit smoking for more than 8 years.

The risk reduction effect for each complication was estimated to be 21% for diabetic nephropathy, 41% for diabetic retinopathy, and 20% for diabetic neuropathy.

Even in the group that quit smoking for 6 to 7 years, the overall risk of microvascular complications was 12% lower than that of continuous smokers. In particular, diabetic neuropathy was confirmed to have a 24% lower risk from this point on.

This does not mean that the risk of diabetes complications will drop significantly when you quit smoking, but that the longer you quit smoking, the more likely health benefits will accumulate.

In fact, the overall microvascular complication rate was 301.9 cases per 10,000 people per year in continuous smokers, but fell to 237.6 cases per year in people who quit smoking for more than 8 years.

Microvascular complications are a representative chronic complication that reduces the quality of life of diabetic patients.

If high blood sugar continues for a long time, small blood vessels throughout the body can be damaged, causing diabetic nephropathy in the kidneys, diabetic retinopathy in the eyes, and diabetic neuropathy in the peripheral nerves.

If nephropathy worsens, kidney function may decline and dialysis or kidney transplantation may be necessary, and in severe cases, retinopathy may cause vision loss. Neuropathy can also cause decreased sensation and pain in the feet, which can lead to diabetic feet and the risk of amputation.

Smoking is considered a factor that further encourages microvascular damage.

Based on previous research, the research team explained that smoking increases the inflammatory response throughout the body and reduces the function of the endothelial cells covering the inside of blood vessels, which can promote microvascular damage in the kidney, retina, and peripheral nerves. Therefore, the interpretation is that if smoking cessation is maintained for a long period of time, the risk of microvascular complications is likely to gradually decrease as these vascular damage factors decrease.

The research team said, "The results of the study show that the effect of reducing the risk of diabetic microvascular complications may become more evident when smoking is continued for a long period of time rather than immediately after quitting," and recommended, "It is never too late to quit smoking at any time for diabetic patients, but it is important to keep it for a long time."