Epidemiology of known diabetes in Lombardy, north Italy. Clinical characteristics and methodological aspects.

Diabetes epidemiology can benefit in Italy from the large network of outpatient diabetic clinics and patients' facilities. A large investigation was carried out in 1988, in a certain area of northern Italy, to estimate the prevalence of known diabetes. Using four information sources, 4547 distinct patients were identified. Through the capture-recapture method we assessed completeness and estimated a prevalence of 3.3%. Prevalence of type 1 diabetes was 0.8 per 1000. Italian age-standardised overall prevalence and developed-world standardised rates were 2.8% and 2.6%, respectively. A representative sample of 2358 patients was characterised through a standard questionnaire. Women were diagnosed about 6 years later than men (58.8 +/- 0.4 vs 52.9 +/- 0.4, P < 0.0001), while the duration of the disease was very similar in both sexes (9.9 +/- 0.2 vs 9.5 +/- 0.2). As regards diabetes therapy, 17.2% of the patients were on diet alone, 62.1% on oral agents and 20.6% on insulin. Among the insulin-treated subjects more than half were on adjuvant therapy with tablets, and only 6.2% were treated with 3 injections/day. Less than half of all the known diabetic subjects had had an ophthalmoscopic examination in the previous 2 years.