Few large epidemiological studies have investigated whether diabetes might increase the risk for, or cause greater severity of, urinary incontinence. The aim of the present study was to investigate the association between diabetes and urinary incontinence, including the possible influence of diabetes on the severity of incontinence. The study was a cross-sectional, population-based, study from the county of Nord-Trøndelag, Norway, from 1995 to 1997. Data were collected by means of questionnaires, simple clinical measurements, and some blood tests. A total of 21,057 women, 20 years or older, answered the questions on both diabetes and incontinence, and 685 women were identified with diabetes. The prevalence of incontinence among women with diabetes was 39% compared to 26% in women without diabetes. The women with diabetes had more urge and mixed incontinence. The associations between diabetes and urge incontinence (OR: 1.49; 95% CI: 1.03-2.16), mixed incontinence (OR: 1.32; 95% CI: 1.05-1.67), and severe incontinence (OR: 1.54; 95% CI: 1.21-1.96) were still significant after adjusting for age, body mass index, parity and smoking. We found a strong association between diabetes and urinary incontinence, especially for urge incontinence and severe degree of incontinence.