Can you tell diabetes from foreskin symptoms? The two seemingly unrelated things are actually related! Recently, Mr. W, 42, visited our urology department for 2 months because of recurrent foreskin fissures and difficulty in upturning. From the medical history, although the patient had been circumcised, he used to upturn freely; however, in the past 2 months, the outer opening of the foreskin was shrinking and chapped, and if it was forcibly upturned, the chapped area was bleeding, red and swollen, with white foreskin scale and a heavy odor. After intercourse with his wife, the local area will be uncomfortable for several days. He was found to be overcircumcised, with a small urethral orifice, chancre, marked redness and swelling, difficulty in turning up the foreskin, prepuce adherence on the inner plate of the foreskin, and an odor. The glans is red and swollen, and there is no obvious discharge from the urethral orifice. The patient was considered to be a “secondary circumcision” with a high probability of diabetes mellitus. He was given insulin to control blood sugar, anti-inflammatory and other symptomatic treatment, as well as diet control and moderate exercise, and the patient recovered quickly. Afterwards, Mr. W came to the clinic several times to thank the physician for associating the two seemingly unrelated things, foreskinitis and diabetes, together. The author summarizes: for recurrent episodes of glans vulgaris with foreskin cracking, presenting specific redness and swelling, which can be accompanied by obvious itching, and conventional anti-inflammatory and other treatments are ineffective, one should think about the possibility of diabetes early; early insulin intensive intervention therapy is the “magic formula” for diabetes treatment, and as the saying goes. As the saying goes, “Open your legs and keep your mouth shut” is the “magic formula” for good blood sugar control.