Trends in diabetes-related mortality in England and Wales between 1975-6 and 1985-6, and regional and ethnic differences in diabetes-related mortality in 1985-6, have been examined. Data from death certificates mentioning diabetes in 1975-6 were compared with those for 1985-6 for different age groups. Data for 1985-6 were also analysed for different regions of England and Wales, and for country of birth. Between 1975-6 and 1985-6, the age-standardized rate of mentioning diabetes rose by 2.7% (95% confidence interval 1.4%, 4.1%) in men of all ages, and fell by 11.7% (10.6, 12.8) in women of all ages. By contrast, the rate of mentioning diabetes in those below 45 years fell by 30.7% (23.0, 37.7) in men and by 26.7% (16.5, 35.6) in women. Deaths in which the underlying cause was ischaemic heart disease (IHD), and where diabetes was also mentioned on the death certificate, rose by 14.4% (11.5, 16.8) in men and did not change significantly in women of all ages, but fell by 18.4% (-35.1, +2.6) in men, and 23.5% (-49.1, +15.2) in women below age 45. This was less favourable than the trend in the general population, where IHD mortality fell by 9.7% in men and 8.3% in women of all ages, and by 31.1% (28.6, 33.5) in men and 40.5% (35.0, 45.5) in women under 45 years.(ABSTRACT TRUNCATED AT 250 WORDS)