| IntroductionType 1 diabetes mellitus (IDDM) is one of the most important chronic diseases of children worldwide. Type 1 diabetes mellitus leads to a 8 - to 10 -fold excess risk of mortality in developed countries, whereas in developing countries, most cases die within a few years. A 350 - fold international gradient in Type 1 diabetes mellitus has been reported. A World Health Organization (WHO) program , Multinational Project for Childhood Diabetes ( Diabetes Mondiale Project or DiaMond Project) , has been developed to investigate and characterize the global incidence, mortality and health care. The objective of the current study was to map the incidence of childhood type 1 diabetes mellitus in Shenyang city, China.Subjects and methodsA retrospective registry was conducted from 1985 to 2003. Capture -recapture methodology, which assumes that independent primary and secondary sources of ascertainment are available, was used to estimate the completeness of registration in line with WHO DIAMOND protocol. The primary source of ascertainment was county or above hospital records, secondary sources varied including schools, social insurance schemes, kindergartens.The definition of a type 1 diabetes mellitus case was according to WHO DiaMond criteria; individuals were diagnosed by a physician, placed on daily insulin injections before his or her 15th birthday, residents in Shenyang City at the time of the first insulin administration, and age 0-14 years at the time of diagnosis.Incidence rates were calculated as the incidence per calendar year and 100,000 individuals at risk. The secular trends in incidence rates were estimated using the Poisson regression analysis.ResultsAccording to the 1990 Chinese census data, there were 1,433,408 children in Shenyang in 1990. During this investigation period, 240 type 1 diabetes melli-tus cases were identified. Of these cases, 230 were found in the hospitals, 104 were registered from a secondary source, and 94 were in both sources. The crude incidence rate was 0.97 per 100,000 with a 95% CI of 0. 85 - 1.09 per 100,000. Base on the capture -recapture method, it was estimated that there were 254 type 1 diabetes mellitus cases (95% CI 242 -266) , with an ascertainment - corrected incidence rate of 1.03 per 100,000. The overall ascertainment rate was 94%. The standard ascertained and corrected incidence rate according to the national age - specific population in 1990 was 0.93 per 100,000.The incidence was significantly higher in girls (1.10 per 100,000) than in boys (0.85 per 100,000).We observed a rising trend in the incidence of cases per 100,000 from 0. 30 in 1985 to 1.19 in 2003 (x2 =49.30, P <0.01). The annual incidence increase during the 19 - year period according to the Poisson model was 9%. The rates of incidence increase in the three age groups were 12% ,7% ,8% for children 0-4,5-9,10-14 age groups respectively, which shows that in relative terms the highest rates of increase occurred in the youngest age group.The incidence rates per 100,000 were 0.60, 1.03, 1.23 for children 0 -4,5 -9,10 -14 age groups respectively, which shows an age - group increase trend in the incidence(x2 = 16.53, P <0.01).Ethnic difference in type 1 diabetes mellitus was not found.The season variation of incidence rate in type 1 diabetes mellitus was not found(x2=1.66,P >0.05).Seasonally of birth in patients with childhood type 1 diabetes mellitus was notfound(x2=3.35,P >0.05).ConclusionThe crude annual incidence rate of childhood type 1 diabetes mellitus was 0.97 per 100,000 with a 95% CI of 0.85 -1.09 per 100,000 in Shenyang cit-y, China. The ascertainment - corrected incidence rate was 1. 03 per 100,000. The incidence was significantly higher in girls than in boys. The annual incidence increase during the 19 - year period according to the Poisson model was 9%. In relative terms the highest rates of increase occurred in the youngest age group.
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