A Tokyo specialist used continuous glucose monitoring to uncover why a patient’s early-morning runs were worsening his glucose levels , and how post-meal walks helped lower his HbA1c.
A Tokyo diabetes specialist says that one man’s stubbornly high HbA1c levels were not caused by lack of effort, but by the way he was exercising. According to the account published by live door News, the patient, a company owner in his 50s, had spent years cutting carbohydrates, scrutinising annual health-check results and going for an early-morning jog before breakfast, yet his HbA1c stayed above 8% for six years. For someone trying hard to do everything right, the result was baffling.
To understand why, the clinic used continuous glucose monitoring, which tracks sugar levels throughout the day rather than relying on a single blood test. The readings showed that his glucose was already high on waking and then climbed to nearly 200 mg/dL after the jog. Because he then ate breakfast, and later lunch before the earlier rise had settled, his blood sugar remained elevated for much of the day. The clinic’s explanation was that the normal early-morning rise in blood sugar, combined with the stress of vigorous exercise, was likely pushing his levels up rather than down. Mayo Clinic says people with diabetes should check glucose before, during and after exercise, while the American Diabetes Association notes that intense activity can briefly raise blood sugar because stress hormones prompt the liver to release glucose.
The answer was not more exercise, but different exercise at a different time. The doctor told him to stop the pre-breakfast jog and instead walk for 15 minutes after each meal. After that change, his post-meal readings became less pronounced and overnight glucose fell from about 140 mg/dL to around 100 mg/dL. Three months later, his HbA1c had improved to 6.6%. Cleveland Clinic says exercise soon after eating can help blunt glucose spikes, which fits the pattern seen in this case.
The doctor cautioned, however, that the lesson should not be taken too broadly. The patient had a family history of diabetes, with his father and brother also affected, so inherited risk almost certainly played a role in his long-term high blood sugar. Other factors, including medication, diet and alcohol intake, can also influence HbA1c, meaning the improvement cannot be credited to exercise alone. The broader point, he said, is that healthy habits only help when they match the body’s actual response. Sometimes, the most important step is not doing more, but finding out what is really happening.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
