A retrospective study was undertaken to estimate the incidence of diabetes mellitus in Norwegian children. Data were collected from all hospitals in the country and from a central insurance register. Eight hundred and forty-five new cases in the age group 0-14 years and with onset in the five-year study period 1973-1977 were detected. The calculated mean annual incidence was 17.6 per 100 000 children, with a year-to-year variation of 15.4-19.3 per 100 000. The geographic variation in incidence was considerable with the lowest rate in the North (6.8/100 000/year) and the highest rates in the South-Eastern part of the country (approx. 20/100 000/year). There was a significantly higher incidence for boys (18.8/100 000/year) than for girls (16.4/100 000/year). The age variation in the incidence rates showed rising values towards a peak at 12 years for girls and a plateau at 12-14 years for boys, with an abrupt decline after 12 and 14 years, respectively. There were more cases with onset in the winter and autumn, with significant peaks in February and October. From these data the prevalence of diabetes mellitus in the age group 0-14 years can be calculated to 1.2 per 1 000 children. In the whole of Norway, about 170 new cases of diabetes mellitus below the age of 15 years can be expected every year. Compared with previous studies, the present data suggest an increasing incidence of childhood diabetes in Norway.
All new cases of Type 1 (insulin-dependent) diabetes mellitus in the 15-29 year age group during the five-year period 1978-1982 were registered using a retrospective technique on a nation-wide basis. A total of 784 newly diagnosed cases were detected, from an average population of 926,192. The degree of ascertainment was almost 90%. The mean yearly incidence for the five-year period was 17.0 per 100,000. The observed incidence is doubled compared to the incidence found in the city of Oslo during the years 1956-1964 (8.8 per 100,000). The male incidence exceeded the female incidence by 12% (p less than 0.05). There was a marked geographic variation in incidence, with a higher incidence in the three southern health regions compared to the two northern, 18.3 vs 13.9 per 100,000 (p less than 0.01). There was a significant seasonal trend in the incidence data (p less than 0.025) with the highest number of new cases detected in the months of January and September and the lowest number in July. In conclusion, the study suggests a two-fold increase of incidence of diabetes mellitus in the age group 15-29 years during the last 2-3 decades and a geographic variation in incidence within the country, pointing to the operation of environmental pathogenic factors.
A retrospective technique was used to register all newly diagnosed cases of diabetes mellitus in Norwegian children 0-14 years of age during the ten-year period 1973-1982. A total of 1,914 newly diagnosed cases were detected, from an average population of 932,037 children. The degree of ascertainment was near to 99%. The male incidence exceeded the female incidence by 12% (p less than 0.02). The mean yearly incidence for the ten-year period was 20.5 per 100,000. Comparing the two five-year periods 1973-1977 and 1978-1982, the mean yearly incidence increased from 18.5 to 22.7 per 100,000 (p less than 0.0001). There was a marked geographic variation with the highest incidence in the south-east and lower incidence in the northern part of the country. However, in the northern part of the country, there was a remarkable increase of the annual incidence from the first to the second five-year period (12.9 vs 19.3 per 100,000). The highest numbers of new cases were detected in the months of January and October, and the lowest numbers in May and July. The seasonal pattern was significantly different from a uniform distribution of new cases throughout the year (p less than 0.001). The age-specific incidence increased towards a peak at 12 years for both sexes. In conclusion, Norway has a high and apparently increasing incidence of childhood diabetes. The geographic variation and secular trend present challenging clues for a search of etio-pathogenic factors.
The mortality status of all individuals in Norway with the onset of Type 1 (insulin-dependent) diabetes mellitus from 1973 through 1982 and age at onset below 15 years was determined as of 1 July 1988. Of the 1908 cases included in the follow-up, 20 had died (15 males and 5 females) and 10 had emigrated. A two-fold increased risk for early mortality was exhibited among this cohort. Life-table analyses did not find sex or age at onset of Type 1 diabetes to be statistically significant predictors of survival when controlling for diabetes duration. A review of death certificates revealed that accidents and suicides accounted for 40% of the deaths in the total cohort and that this cause of death occurred only among male subjects. Acute diabetes related complications were the underlying causes of death for 35% of the subjects. Diabetic renal disease and death by cardiovascular disease were not documented in this young cohort with a maximum age of 30 years and maximum diabetes duration of 15.5 years. This is the first mortality report of a population-based registered cohort of Type 1 diabetic patients for Norway. While still being at increased risk for premature death, this cohort appears to be at decreased risk of early death when compared to a cohort of young diabetic patients from Oslo, Norway diagnosed in 1925-1955, suggesting improvements in the survival of individuals with Type 1 diabetes in Norway.
BACKGROUND: Data on the relationship between Th2-biased atopic disorders and Th1-biased autoimmune diseases such as type 1 diabetes are conflicting. Many studies have not defined the time sequence of disease appearance, and few have investigated the role of candidate risk factors. OBJECTIVE: The objective was to investigate whether the presence of parents' report of physician-diagnosed atopic disorders is lower among cases of type 1 diabetes before diagnosis, as compared with population-based control subjects, and whether this may be explained by candidate risk factors such as day-care attendance, breastfeeding habits, and perinatal factors. METHODS: We designed a population-based case-control study in Norway with 545 cases of childhood-onset type 1 diabetes and 1668 control subjects. Families were contacted by mail, and they completed a questionnaire on physician-diagnosed atopic eczema, allergic rhino-conjunctivitis and asthma, and other relevant factors. Data on birth order, maternal age at delivery, birth weight, gestational age, pre-eclampsia, and caesarean section were obtained from the Medical Birth Registry of Norway by record linkage. RESULTS: Atopic eczema was inversely associated with risk of type 1 diabetes, odds ratio=0.55 (95% confidence interval 0.35-0.87) after adjustment for age, sex, maternal education, day-care attendance, duration of exclusive breastfeeding, and perinatal factors. Allergic rhino-conjunctivitis and asthma were not significantly associated with type 1 diabetes. CONCLUSIONS: Atopic eczema was associated with a lower risk of type 1 diabetes, independent of a number of candidate risk factors, suggesting that it may confer partial protection against type 1 diabetes.
OBJECTIVE: To compare age-standardized incidence rates of diabetes in children 0-14 yr of age and cows' milk consumption in various countries. RESEARCH DESIGN AND METHODS: Ecological correlation study. Only incidence rates from diabetes registries carefully validated by the Diabetes Epidemiology Research International Study Group were used-Finland, Sweden, Norway, Great Britain, Denmark, United States, New Zealand, Netherlands, Canada, France, Israel, and Japan. Data on fluid cows' milk consumption in corresponding countries were obtained from the International Dairy Federation. RESULTS: Correlation between milk consumption and incidence of insulin-dependent diabetes mellitus (IDDM) was 0.96. The data fit a linear regression model, and analysis showed that 94% of the geographic variation in incidence might be explained by differences in milk consumption. CONCLUSIONS: The results support the hypothesis that cows' milk may contain a triggering factor for the development of IDDM.
AIMS/HYPOTHESIS: To test whether cod liver oil or vitamin D supplements either taken by the mother during pregnancy or by the child in the first year of life is associated with lower risk of Type I (insulin-dependent) diabetes mellitus in children. METHODS: We carried out a population-based case control study in Vest-Agder county of Norway, evaluating the use of supplements by a mailed questionnaire. We received responses from 85 diabetic subjects and 1,071 control subjects. Odds ratios (OR) with 95% confidence intervals (CI) were estimated using logistic regression analyses. RESULTS: When mothers took cod liver oil during pregnancy their offspring had a lower risk of diabetes. The unadjusted OR was 0.30, 95% CI: (0.12 to 0.75), p = 0.01. This association changed very little and was still significant after adjusting for age, sex, breastfeeding and maternal education. Mothers taking multivitamin supplements during pregnancy [adjusted OR= 1.11, 95% CI: (0.69 to 1.77)], infants taking cod liver oil in the first year of life [adjusted OR = 0.82, 95 % CI: (0.47 to 1.42) and the use of other vitamin D supplements in the first year of life [adjusted OR = 1.27, 95 % CI: (0.70 to 2.31)] was not [corrected] significantly associated with the risk of diabetes. CONCLUSION/INTERPRETATION: We found that cod liver oil taken during pregnancy was associated with reduced risk of Type I diabetes in the offspring. This suggests that vitamin D or the n-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid in the cod liver oil, or both, have a protective effect against Type I diabetes.