Great Gidayū, Who Said, “I Underestimated Diabetes,” Dies at 67; Doctor Warns of a Dangerous Common Factor Among Those Who End Up on Dialysis

On September 7, Great Gidayu, beloved as a member of the “Takeshi Corps,” passed away at the age of 67.

During his lifetime, Mr. Gidayu had publicly disclosed that he suffered from diabetes and was undergoing dialysis. He chronicled his experience battling the disease in his book *I Have Diabetes, Mom!* (Gentosha).

“I really underestimated diabetes.”

Gitayu once reflected on his illness in this way.

The cause of death has not been disclosed, and a causal relationship with diabetes or kidney failure remains unclear. However, the words of Gitayu—who had spoken out about diabetes and dialysis for many years—once again drive home the terrifying reality of this disease.

Diabetes is not a disease that suddenly presents with severe symptoms. “My blood sugar is a little high,” “My blood pressure is a little high”—even while living and working as usual with such abnormalities—which are commonly seen in health checkups—the kidneys may be quietly sustaining damage.

Some people progress from diabetes to dialysis, while others manage to protect their kidneys and maintain their health. Where does this fork in the road lie? We asked Dr. Tadashi Tomohiro, Chairman of Noborito Clinic, who treats numerous patients with lifestyle-related diseases (quotes below are from Dr. Tomohiro).

“I’m fine because I feel fine”—that’s the scariest thing

“The scary thing about diabetes is that there are almost no noticeable symptoms in the early stages. It’s not uncommon for people to work, eat, and go about their daily lives as usual even when their blood sugar levels are high. They tend to think, ‘I don’t feel sick, so I’m fine.’ However, even during that time, damage caused by high blood sugar is gradually accumulating in the body.”

One of the most common complications of diabetes is diabetic nephropathy, a condition in which kidney function gradually declines. The kidneys are responsible for filtering blood and excreting waste products, excess fluid, and salt as urine. The “glomeruli,” which filter the blood, are delicate structures formed by clusters of tiny capillaries.

“When high blood sugar persists, it puts a strain on the kidneys’ tiny blood vessels and glomeruli. Over time, a protein called albumin—which normally is hardly ever excreted in urine—begins to leak into the urine, and as the condition progresses further, kidney function itself declines.

When the kidneys alone can no longer adequately process the body’s waste products and excess fluid, treatments such as dialysis or a kidney transplant become necessary. However, even as kidney function begins to decline, symptoms such as pain do not appear. In some cases, no obvious symptoms may appear until the condition has progressed significantly.”

“It doesn’t hurt,” “I can still work,” “I have an appetite.”

But you shouldn’t feel reassured by these signs alone. Diabetic nephropathy doesn’t happen suddenly one day. It progresses gradually over a long period of time.

However, it’s important to note that “diabetes does not automatically mean dialysis.”

“Just because you have diabetes doesn’t mean you’ll inevitably end up on dialysis. By managing not only blood sugar but also blood pressure, lipids, and weight—and by regularly monitoring the condition of your kidneys—you can prevent a decline in kidney function. The real danger is thinking you’re ‘cured’ just because your test results have improved, and then stopping your medication or skipping follow-up appointments on your own.”

Dr. Tomohiro emphasizes that the stage long before “the point just before needing dialysis” is far more important.

“Diabetes patients sometimes ask me, ‘At what point will I need dialysis?’ But what’s important isn’t knowing the exact ‘danger zone’ numbers. ‘My blood sugar is a little high. My blood pressure is a little high. My kidney function has started to decline slightly. But I don’t feel sick’—what you do at this stage is what matters most.”

Whether or Not to Ignore “Minor Issues” Is the Turning Point 10 Years Down the Road

Even when a health checkup flags a condition as “requiring attention,” many people tend to ignore it if they have no symptoms. Dr. Tomohiro warns that it is precisely this mindset—thinking, “It’s only a little, so it’s fine”—that people need to be wary of.

“Your blood sugar is a little high, your blood pressure is a little high. Just because you’re told that doesn’t mean you’ll start feeling unwell the very next day. So people tend to think, ‘I’ll just wait and see until next year’s checkup.’

But if that continues for five or ten years, the strain on your kidneys will accumulate. Do you ignore it, thinking, ‘I’m still fine,’ or do you reassess your lifestyle and treatment at that stage? That accumulation will affect your kidney function 10 or 20 years down the line.”

As kidney function continues to decline, symptoms such as swelling, fatigue, loss of appetite, and shortness of breath due to anemia may appear.

“There are cases where patients come to the hospital with swelling or shortness of breath only to find that their kidney function has already declined significantly. It’s not a matter of thinking, ‘I’ll just go to the hospital when symptoms appear.’ Instead, it’s crucial to detect changes through testing and begin treatment before symptoms even appear.”

So, how can you detect changes in kidney function?

The key values to check during a health screening are “creatinine (Cr)” and “eGFR (estimated glomerular filtration rate).”Creatinine is a waste product produced by muscle metabolism; it is normally filtered by the kidneys and excreted in the urine. eGFR is an indicator used to estimate how effectively the kidneys are filtering blood.

“Even if you think your creatinine is ‘just a little high,’ you may find that your eGFR has dropped to the 40s or 50s. Generally, an eGFR below 60 that persists for three months or longer is one of the criteria for diagnosing chronic kidney disease (CKD).If this is pointed out during a health checkup, it’s important not to ignore it just because ‘it’s only a little.’”

For people with diabetes, “urinary protein” is also an important factor.

“In diabetic kidney disease, urinary protein levels may begin to rise even before the eGFR drops significantly. Therefore, you cannot assume that ‘since blood sugar levels are stable, the kidneys must be fine’ just by looking at HbA1c, which is an indicator of diabetes. It’s important to assess kidney function through both blood and urine tests.”

There is an important point to understand about chronic kidney disease: “Once kidney function has significantly declined, it is difficult to restore it to its original state.” Dr. Tomohiro emphasizes that “this is extremely important to keep in mind when considering kidney disease.”

“Once kidney function declines chronically, it is generally difficult to restore the kidneys to their original state. If the eGFR drops to 50, you cannot usually expect it to return to 80 or 90 simply by improving your lifestyle. That is precisely why, with kidney disease, it is crucial to adopt the mindset of ‘preventing further deterioration’ rather than thinking, ‘I’ll just treat it once it gets worse.’”

What can be done to protect the remaining kidney function?

“I tell my patients, ‘Let’s take good care of the kidney function you have left for the rest of your life.’ This means carefully managing blood sugar and blood pressure, avoiding excessive salt intake, and maintaining a healthy weight. It also means getting regular checkups to detect changes in kidney function early.

By taking steps while kidney function is still sufficient, it’s possible to slow the rate of decline, delay the need for dialysis as long as possible, or even prevent the need for dialysis altogether. The key to treating kidney disease is not so much restoring lost function as it is preserving the kidney function you have now for as long as possible.”

In other words, “now, while your kidneys are still functioning,” is the crucial time to take action that will shape your future.

Three times a week, four hours each session—how does life change with hemodialysis?

When kidney function declines significantly and the body can no longer adequately remove waste products and excess fluid, hemodialysis may become necessary. Standard hemodialysis is performed three times a week, with each session lasting about four hours.

“Dialysis is a vital treatment that sustains life. However, it’s not without its burdens on daily life. If you’re employed, you’ll need to adjust your work schedule, and you’ll also need to manage your diet, fluid intake, and weight.”

Some people have maintained this routine for many years, undergoing nighttime dialysis after work and returning home late at night. When traveling or going on business trips, they must also find medical facilities where they can receive dialysis in advance and make appointments.

“Some patients tell me, ‘I wish I’d paid more attention to my blood sugar and blood pressure earlier’ or ‘I shouldn’t have neglected my health checkups’ after starting dialysis. Some only realize how grateful they should be for their kidneys working for them every day once they start dialysis.”

This echoes the words Gidayu left behind before his death: “I took diabetes for granted.”

What can be done to protect the kidneys from diabetes? Dr. Tomohiro says, “There’s no need to do anything special.”

“First, don’t stop treatment on your own. On top of that, manage your blood sugar, blood pressure, lipids, and weight. Don’t consume too much salt. Continue exercising within your limits. And regularly check your eGFR and urine protein levels.

“Advances in diabetes treatment mean we’re now in an era where medications are chosen not only to lower blood sugar but also to protect the kidneys and heart. By continuing treatment from an early stage, there’s a lot that can be done.”

It’s hard for people in their 30s and 40s to imagine undergoing dialysis 10 or 20 years from now—especially when they aren’t experiencing any pain or discomfort. However, how you act during this “asymptomatic period” is crucial. Dr. Tomohiro concludes with this appeal:

“I hope people won’t think, ‘I’m fine because I don’t have symptoms yet,’ but rather, ‘There are things I can do precisely because I don’t have symptoms yet.’ Even if it’s difficult to restore kidney function once it has declined, there are steps you can take to protect your current kidney function and prevent further deterioration. If an abnormality is pointed out during a health checkup, I hope you’ll use that as an opportunity to reevaluate your lifestyle and treatment for the sake of your future self.”

“I’m still fine.”

The time when you feel that way is not the time to ignore the issue.

It’s the time when “it’s not too late.”

The regret expressed by the late Great Gidayū—that he “underestimated diabetes.”
Those words resonate most deeply today with the very people who think, “I’m still fine.”