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The aims of this survey were (1) to estimate the prevalence of known diabetes mellitus in 1988 in Casale Monferrato (Northern Italy); (2) to validate different data sources available in Italy; (3) to identify a population-based cohort of diabetic patients. Multiple independent data sources were used and the capture-recapture method was applied to estimate the completeness of ascertainment of the survey. The primary data source was the list of all patients attending the diabetic clinic or those referred by family physicians and paediatricians of the area. The secondary data sources were the list of hospital discharges, the prescriptions data source and the list of all people using reagent strips and insulin syringes. On 1 October 1988 (the cut-off date) 2,069 cases of known diabetes were identified. The estimated completeness of ascertainment of the survey was 91%. Prevalence of known diabetes, Type 1 (insulin-dependent), Type 2 (non-insulin-dependent) and insulin-treated diabetes were, respectively, 2.21% (95% CI 2.13-2.29), 0.80/1,000 (0.62-0.98) and 2.10% (2.01-2.19), 2.92/1,000 (2.57-3.27). A higher prevalence of Type 2 diabetes was observed in women (2.30%, 2.18-2.42) than in men (1.88%, 1.76-2.00). Age-specific prevalence of Type 2 diabetes increased with age. Computerized data sources routinely available in the Piedmont Region (hospital discharges and prescriptions data sources) showed a low completeness of ascertainment when considered together (65%, 1,338 of 2,069), indicating the need to involve the diabetic clinic and family physicians in the ascertainment of known diabetes. In conclusion, the prevalence of known diabetes in Italy was lower than in Northern Europe and the United States.

Dietary constituents other than glucose can influence insulin secretion in non-insulin-dependent diabetes mellitus and administration of a standard mixed meal has been proposed as a more physiological test in regard to human diet for evaluating the patient both at the time of diagnosis and during follow-up. This study was carried out to compare the effects of a standard meal and the oral glucose tolerance test on glucose, insulin and C-peptide plasma levels in four groups of subjects: healthy controls, subjects with impaired glucose tolerance, patients with mild non-insulin-dependent diabetes, and non-insulin-dependent diabetic patients with secondary failure to oral agents. Plasma glucose values were significantly higher after the oral glucose tolerance test than after the mixed meal in all four groups of subjects. Plasma insulin and C-peptide values were similar during the two tests in all groups of subjects except in non-insulin-dependent diabetics with secondary failure (flattened curves). Insulin and C-peptide responses per unit rise in blood glucose were significantly higher after the oral glucose tolerance test than after the mixed meal both in mild non-insulin-dependent diabetics (P less than 0.05 and P less than 0.05) and in non-insulin-dependent diabetics in secondary failure (P less than 0.01 and P less than 0.05). There was significant correlation between oral glucose tolerance test and mixed meal glucose incremental areas (r = 0.511, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)