Diabetes mellitus in north Sweden: prevalence assessed from prescriptions for anti-diabetic agents

A prescription inventory was performed over a period of 3 months in all pharmacies in Sweden's northernmost province. Norrbotten, in order to assess the prevalence of diabetes treated with insulin and oral anti-diabetic agents. A total of 4869 prescriptions were collected from 3482 individuals, of whom 1746 (50.1%) were men. The prevalence of drug-treated diabetes was thus 13.27/1000 inhabitants (95% confidence interval (CI) 12.8-13.7) in the province. Nearly half (47.9%) of all drug-treated diabetics were treated with insulin and the majority (74%) were over 55 years of age, with only 449 (13%) being less than 40 years old. The prevalence of diabetes was highest in individuals aged 75-84 years; in this age group it was 55.47/1000 (95% CI 50.9-58.7). There was considerable regional variation in the prevalence of diabetes in Norrbotten, with a mean prevalence of 23.84/1000 (95% CI 22.1-25.6) in the municipalities in the Torneå Valley, compared to 13.08/1000 (95% CI 1.19-1.28) for the remainder of Norrbotten. While there was no difference in the prevalence of drug-treated diabetes between men and women in the province as a whole, a slightly higher prevalence was found in women (27.41 vs. 24.73/1000) in the Torneå Valley. The prevalence of diabetes mellitus in individuals over 40 years of age was 36.62/1000 (95% CI 3.73-4.36) in The Torneå Valley, 24.38/1000 (95% CI 22.8-24.7) in the remainder of Norrbotten, and 27.88/1000 (95% CI 2.50-2.68) in the province as a whole. The estimated prevalence of diabetes mellitus in Norrbotten, including patients treated by diet alone, was of the order of 20.21/1000, with a prevalence of 40.00/1000 in subjects over the age of 40 years. Thus the prevalence of diabetes appears to be higher in the Torneå Valley than in the rest of Norrbotten, while it is apparently lower than has been reported in North Finland.