Does Taking Diabetes Medication Decrease Kidney and Pancreas Function? The Truth Revealed by an Expert

Among diabetes patients, there is an anxiety that taking diabetes medication for a long time will damage the kidneys or decrease pancreatic function, eventually requiring insulin injections. Professor Son Jang-won of the Department of Endocrinology at The Catholic University of Korea Bucheon St. Mary's Hospital, appearing on the health and medical specialty channel HiDoc, explains that these concerns stem from misunderstandings of the disease progression and the characteristics of the medications.

The Background of the Misconception that Diabetes Medication Damages the Kidneys and Pancreas

Many patients tend to think that if their kidney function decreases while taking diabetes medication, it is because of the drug. However, Professor Son explains this using a 'firefighter analogy.' Just as a firefighter responding to a fire scene might be misunderstood as having caused the fire, it is more reasonable to understand that kidney disease occurring during the process of a diabetes patient taking medication is 'diabetic nephropathy,' a complication of diabetes itself, rather than a side effect of the drug.

In fact, because drugs used as first-line treatments, such as metformin, are excreted through the kidneys, if kidney function (glomerular filtration rate) falls below a certain level, the dosage must be reduced for safety, or the medication must be temporarily suspended during CT scans. Safety measures are required, such as adjusting the metformin dosage when the glomerular filtration rate typically decreases below 45 or 32, and these measures themselves become a cause for the misunderstanding that 'the medicine is bad for the kidneys.'

The concerns regarding decreased pancreatic function are the same. Diabetes begins at the time of diagnosis with only 50% or, in severe cases, about 20% of pancreatic beta-cell function remaining. It is like starting with a mobile phone battery that has less than one bar left. As the disease progresses, the remaining function is lost, and the need for insulin treatment arises; this is often not due to the medication, but rather the natural course of the disease where the remaining battery is completely depleted due to high blood sugar environments or failure in weight control.

However, in the case of 'sulfonylureas,' which directly stimulate insulin secretion from the pancreas, there is a characteristic that long-term use can cause the pancreas to keep working, which may rapidly exhaust its function. Due to this characteristic, concerns about weakening pancreatic function are sometimes raised in patients using sulfonylureas.

Drug Combinations that Preserve Pancreatic Function and the Role of Insulin Treatment

Professor Son emphasizes that an appropriate combination of medications is important to maintain pancreatic function for a long time. While sulfonylureas stimulate the pancreas, drugs such as SGLT2 inhibitors or GLP-1 receptor agonists can help the pancreas rest by improving insulin resistance and play a role in preserving beta-cell function. Therefore, for early-stage patients who respond well to sulfonylureas, using them is appropriate, but a strategy of appropriately combining or sequentially using drugs that can allow the pancreas to rest can help delay the loss of pancreatic function.

He also corrected misconceptions about insulin injection treatment. There is a worry that injecting insulin from the outside will stop insulin secretion within the body, but he explained that rather, improving the high blood sugar environment through timely insulin treatment reduces the burden on pancreatic beta-cells, which helps preserve cell function in the long term. Insulin serves as a very powerful blood glucose enhancer.

Furthermore, regarding the common belief that once pancreatic function is damaged, it is difficult to recover, he replied, "That is not necessarily true." In the case of early-stage patients with a short duration of illness and good weight management and lifestyle correction, beta-cell function can be well maintained for a considerable period through appropriate drug treatment. In fact, not all patients require insulin treatment, and most patients can be controlled with oral medications as beta-cell function is maintained. However, if high blood sugar is neglected and pancreatic cells reach a state of fibrosis or dedifferentiation, it becomes difficult to reverse, so 'timely treatment' is more important than anything else.

The Danger of Arbitrarily Stopping Medication and the Value of Metformin

Many patients stop their medication on their own when their blood sugar levels come out normal. Professor Son warns that stable blood sugar is a sign that the medication treatment is working effectively, so they must consult with their primary physician. If taking too many medications is cumbersome, the direction of reduction should be decided through consultation with a doctor, such as changing to recently released combination drugs or medications taken once a day. Arbitrary discontinuation eventually leads to high blood sugar, which can cause acute symptoms such as thirst.

Diabetes management is like a 'team sport' that does not look at blood sugar alone but manages hypertension and hyperlipidemia together. If blood sugar control is the key player in a soccer match, managing blood pressure and lipids plays the role of defenders and goalkeepers, with the ultimate goal being to prevent cardiovascular complications. Therefore, using multiple medications should be understood as part of an overall treatment strategy to lower cardiovascular complications.

Finally, he mentioned the status of metformin as a first-line drug and recent changes. As the diabetes treatment paradigm shifts toward complication-tailored treatment, SGLT2 inhibitors or GLP-1 drugs may be prioritized for certain patients, which may give the impression that metformin is being excluded from first-line treatment; however, metformin remains a very important drug whose safety and cost-effectiveness have been proven through long-term research.

Meanwhile, regarding the rumor that metformin has anti-aging or life-extending effects, Professor Son mentioned, "It is an interesting hypothesis, and there are positive studies such as increasing cellular autophagy." This is because preclinical studies exist suggesting that metformin can improve mitochondrial function within cells or improve aged cells by increasing cellular autophagy. However, he added that since there are no clinical studies on the general population without diabetes, caution is needed when taking it like an anti-aging supplement.