Incidence of Type 1 (insulin-dependent) diabetes mellitus in Catalonia, Spain

Summary The incidence of Type 1 (insulin-dependent) diabetes mellitus was prospectively evaluated in Catalonia, Spain in patients up to 30 years of age during the period 1987–1990. The population at risk (0–29 years) consisted of 2,690,394 inhabitants (total population of Catalonia 5,978,638). All the cases were independently identified from four sources: endocrinologists, sales of blood glucose monitors and insulin pen injectors, diabetes societies and diabetic summer camps. The degree of ascertainment was 90.1 %. The overall observed incidence rate was 10.7 per 100,000 per year, being 11.5 per 100,000 per year in the 0–14 age group. The incidence in males (12.0 per 100,000 per year) was higher than in females (9.3 per 100,000 per year), with a male/female ratio of 1.36/l. The sex differences were only present in cases over 14 years of age. Age specific incidence rates per 100,000 per year were 4.4 (confidence interval 95%: 3.2–5.7) in the age group 0–4, 9.9 (8.5–11.4) in 5–9, 17.5 (15.7–19.4) in 10–14, 11.4 (9.9–13.0) in 15–19, 11.3 (9.7–13.0) in 20–24 and 8.5 (7.2–9.9) in 25–29. There was a seasonal onset pattern, with the highest incidence in winter (December–February). We conclude that the incidence of Type 1 diabetes observed in Catalonia during the period 1987–1990 is higher than that recently reported in other Mediterranean countries. This study offers the first standardized data on Type 1 diabetes incidence in Catalonia, including cases up to 30 years, and contributes to the knowledge of the epidemiology of diabetes in South Europe.     

The incidence of Type 1 (insulin-dependent) diabetes mellitus 15–29 years in Norway 1978–1982

Summary 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< 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< 0.01). There was a significant seasonal trend in the incidence data (p< 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.     

Incidence of IDDM during 1988–1992 in Zagreb,Croatia

Summary The objective of this study was to determine the incidence of insulin-dependent diabetes mellitus (IDDM) in the population of Zagreb, Croatia, during 1988–1992. A centralized diabetes registry was the primary source of data, while secondary sources were used to assess ascertainment. A total of 282 new cases of IDDM were diagnosed in the study period, the primary and secondary sources identifying annually 93–100% of the cases. The annual incidence rate ranged from 5.6 per 100,000 to 6.6 per 100,000. Early fatality in persons older than 50 years was the major cause of underascertainment. The incidence peaked in the 10–14 years age group (12.4 per 100,000), and remained stable after age 24 years. Males had a significantly higher incidence in the 5–9 and 24–44 years age groups. In the 45–54 years age group, females had a significantly higher incidence. No seasonality was observed. Despite the war conditions in Croatia, the low overall IDDM incidence rates did not change significantly during the study period.Abbreviations IDDM Insulin-dependent diabetes mellitus - DKA diabetic ketoacidosis     

Incidence of juvenile Type 1 (insulin-dependent) diabetes mellitus in France

Summary The incidence rate of juvenile Type 1 (insulin-dependent) diabetes in France was reported as the lowest in Europe 13 years ago, but during the recent years increasing rates have been observed in different European countries. A prospective programme has been designed to study the incidence rate of Type 1 diabetes in patients up to 20 years of age in four regions located in the north and south of France (population <20 years = 2.31 million inhabitants; 15% of the French population). All cases were independently identified by four specially trained research assistants through hospital admission files, paediatricians, diabetologists and general practitioners. A specific questionnaire was filled out for each newly diagnosed case. Degree of ascertainment was 96% with the data from Sécurité Sociale, the French National Health Insurance. In 1988, 166 cases of juvenile Type 1 diabetes were identified. The incidence rate was 7.17 cases per 10⁵ children (95% confidence interval = 6.1–8.2/10⁵). The values were not statistically different among the four regions. Age specific incidence rates were as follows: 0–4 years = 3.8; 5–9 years = 8.0; 10–14 years = 9.7 and 15–19 years = 7.3/10⁵. Sex ratio was 1.2 (male/female). These data indicate that incidence of juvenile Type 1 diabetes in France was higher in 1988 than previously reported but remains lower than in Northern Europe. This is consistent with the concept of a north to south gradient of the disease.     

Increasing trend in Type 1 (insulin-dependent) diabetes mellitus in childhood in Finland

Summary The Central Drug Registry in Finland ascertained 5,920 incident cases of Type 1 (insulin-dependent) diabetes mellitus diagnosed under the age of 15 years, during 1965–1984. The incidence was higher for males 29.2/100,000 (95% confidence intervals 28.2–30.2/100,000) than for females 26.1/100,000 (25.1–27.1/100,000). A non-linear increase in incidence with age was confirmed, with peaks at ages 2,9 and 14 years in males and at 3,5–6 and 11 years in females. A significant temporal variation in incidence was found, adjusting for age and sex. During 1965 to 1984 the incidence rose by about 57% or by 2.4% annually. However, a non-linear curve with two incidence peaks in 1978 and 1983 would better describe the temporal pattern than a linear trend. There was no significant difference in the temporal variation between males and females. The changes in diabetes risk appeared to affect proportionally all age groups under 15 years. Two possible mechanisms were explored: a calendar period effect vs a birth cohort effect. The calendar time period effect was significant alone and also when adjusted for the birth cohort effect. One the contrary, the birth cohort effect was not significant, when adjusted for the calendar period effect. In conclusion, over the past two decades, the incidence of childhood Type 1 diabetes in Finland has increased by about 57%. The pattern of change was a steady rising background incidence superimposed by sudden outbreaks suggesting environmental causative factors.     

Incidence of Type 1 (insulin-dependent) diabetes mellitus in subjects 0–14 years of age in the Comunidad of Madrid,Spain

Summary A retrospective, population-based registry was established in the Comunidad of Madrid, Spain (total population: 4,780,572; under age 15: 1,105,243) to investigate the epidemiology of Type 1 (insulin-dependent) diabetes mellitus. Included were all cases diagnosed with diabetes between 1985 and 1988, with age onset less than 15 years, and using insulin at discharge from hospital. Using the capture-recapture method employing hospital records as the primary source and membership files of the Spanish Diabetic Association as the secondary source, the ascertainment was 90%. The overall annual incidence was estimated to be 11.3/100,000 (Poisson 95% confidence interval: 10.3–12.4). There was no temporal increase in incidence, nor was there a significant sex difference in incidence rates, either overall or by year. The seasonal onset pattern showed the highest incidence in winter (December–February) and lowest in summer (June–August) (r=7.36, p<0.05). The age-adjusted (world standard) incidence of 10.9/100,000 was inconsistent with the hypothesis of a north-south gradient in diabetes risk.     

Epidemiology of childhood diabetes mellitus in Finland--background of a nationwide study of type 1 (insulin-dependent) diabetes mellitus. The Childhood Diabetes in Finland (DiMe) Study Group.

Summary A nationwide study of childhood Type 1 (insulin-dependent) diabetes mellitus was established in 1986 in Finland, the country with the highest incidence of this disease worldwide. The aim of the project called Childhood Diabetes in Finland is to evaluate the role of genetic, environmental and immunological factors and particularly the interaction between genetic and environmental factors in the development of Type 1 diabetes. From September 1986 to April 1989, 801 families with a newly-diagnosed child aged 14 years or younger at the time of diagnosis were invited to participate in this study. The vast majority of the families agreed to participate in the comprehensive investigations of the study. HLA genotypes and haplotypes were determined in 757 families (95%). Our study also incorporates a prospective family study among non-diabetic siblings aged 3–19 years, and two case-control studies among the youngonset cases of Type 1 diabetes. During 1987–1989, the overall incidence of Type 1 diabetes was about 35.2 per 100,000 per year. It was higher in boys (38.4) than in girls (32.2). There was no clear geographic variation in incidence among the 12 provinces of Finland. Of the 1,014 cases during these 3 years only six cases were diagnosed before their first birthday. The incidence was high already in the age group 1–4-years old: 33.2 in boys and 29.5 in girls. Of the 801 families 90 (11.2%) were multiple case families, of which 66 had a parent with Type 1 diabetes at the time of diagnosis of the proband. The prevalence of Type 1 diabetes in the parents of these newly-diagnosed diabetic children was higher in fathers (5.7%) than in mothers (2.6%).     

Incidence and prevalence of Type 1 (insulin-dependent) diabetes mellitus in Icelandic children 1970–1989

Summary Through use of primary and secondary data sources for registration and validation, the incidence and prevalence of Type 1 (insulin-dependent) diabetes mellitus in children aged 0–14 years in Iceland has been completely ascertained for the years 1970–1989. The age-adjusted mean annual incidence per 100,000 for the 20-year period was 9.4 (95% confidence interval 7.8–11.3); similar for boys (9.9; 7.7–12.7) and girls (8.8; 6.7–11.5). Between 1970–1979 the incidence was 8.0 (6.0–10.6) and between 1980–1989 it was comparable at 10.8 (8.4–13.8) (p>0.10). By Poisson regression analysis the variation in incidence was related to age at diagnosis (p<0.001), while a linear trend for calendar year at diagnosis did not reach statistical significance (p=0.07). A quadratic curve, however, better described the temporal variation in incidence (p<0.05). The total prevalence per 1,000 by the end of 1979 and 1989 was similar, 0.45 (0.30–0.65) and 0.57 (0.40–0.79), respectively. In conclusion, this study confirms that both the incidence and prevalence of childhood Type 1 diabetes in Iceland are low compared to the other Nordic countries. The findings may suggest a causative role for environmental factors that are not related to latitude or ambient temperature.     

Prospective incidence study of diabetes mellitus in New Zealand children aged 0 to 14 years

Aims/hypothesis The aim of this study was to establish the incidence of type 1 and type 2 diabetes mellitus in children aged 0–14 years.Methods The New Zealand Paediatric Surveillance Unit sought monthly reporting of diabetes mellitus cases from paediatricians. All resident children aged below 15 years (1996 census risk population 832,000) who met the criteria for diagnosis of diabetes mellitus from 1 January 1999 to 31 December 2000 were included. The average annual incidence of type 1 and type 2 diabetes was calculated, as were incidence rates according to age, sex, region, ethnicity and season. Case ascertainment was estimated using hospital admission data.Results There were 315 valid reports of new cases of diabetes. Of these, 298 (94.6%) had type 1 diabetes, 12 (3.8%) had type 2 diabetes and five had other specified types of diabetes. The average annual incidence of type 1 diabetes was 17.9/100,000 (95% CI: 15.9–20/100,000). Children in the South Island had a 1.5-fold higher incidence than children in the North Island, which was largely accounted for by the variation in incidence with ethnicity, in that the European rate was 4.5 times higher than the Maori rate. The average annual incidence of type 2 diabetes was 0.84/100,000 (95% CI: 0.37–1.26/100,000). Estimated case ascertainment rate was 95.2%.Conclusions/interpretation Type 1 diabetes incidence has doubled over the past three decades. The geographical differences previously described have persisted, and are largely explained by the ethnic variation in incidence. This population includes young adolescents with type 2 diabetes. These findings are in keeping with international trends.     

The epidemiology of Type 1 diabetes mellitus is not the same in young adults as in children

Aims/hypothesis This prospective study examined the epidemiology of Type 1 diabetes in young adults in Europe.Methods We ascertained incident cases of Type 1 diabetes in the 15 to 29 years (both inclusive) age group throughout Europe over a period of 2 years. Diabetes registries in nine countries, in which incidence rates for Type 1 diabetes in the 0 to 14 age group were available, took part. Incidence rates were estimated per 100000 person years and standardised for sex and age. Cumulative incidences per 1000 from birth to age 30 were estimated. Heterogeneity between centres was tested with a Poisson regression model.Results A total of 2112 diabetes cases were ascertained in 1996 and 1997, of which 61.4% were considered to be Type 1 diabetes. Completeness of ascertainment varied from 70 to 90%. Standardised incidence varied from 4.8 per 100000 person years to 13.4 per 100000 person years. The male–female ratio was estimated to be one or more, and in the 25 to 29 age group 1.5 or more in all countries. Cumulative incidences for males and females indicate that the former exceeds the latter from age 24. In the two centres with highest childhood incidence, this applied already from 14 years of age.Conclusions/interpretation The incidence of Type 1 diabetes in adults is lower than in children and the range of incidence is also reduced, with a less than threefold variation in adults, against an eightfold variation in children. There is a male excess in incidence, especially in the age group 25 to 29 years.Abbreviations EURODIAB TIGER European Diabetes: Type I Genetic Epidemiology Resource     

Male predominance of Type 1 (insulin-dependent) diabetes mellitus in young adults: results from a 5-year prospective nationwide study of the 15–34-year age group in Sweden

Summary The incidence of diabetes mellitus in Sweden in the 15–34 year age group was prospectively studied on a nationwide basis, beginning 1 January 1983. A total of 1,214 male and 720 female cases of newly-diagnosed (excluding gestational) diabetes were reported over a 5-year period. This corresponds to an incidence of 20.5 per 100,000/year in male subjects and 12.7 per 100,000/year in female subjects. Most cases were classified as Type 1 (insulin-dependent) diabetes, with an incidence of 15.9 in males and 8.6 in females. The incidence of Type 1 diabetes decreased gradually with age, while the incidence of Type 2 (non-insulin-dependent) diabetes increased. A male predominance was found in all age groups, with a male-to-female ratio of 1.81 for Type 1 diabetes and 1.31 for Type 2 diabetes. Maximum blood glucose concentration at diagnosis was significantly higher in males than in females in both Type 1 and Type 2 diabetic subjects. In contrast, the percent desirable weight was significantly higher in females, both in Type 1 and Type 2 diabetic subjects. The difference in diabetes incidence therefore cannot be attributed to any methodological error. The present finding of a marked male predominance after puberty in Type 1 diabetes in an ethnically quite homogeneous population supports the hypothesis that environmental risk factors and life-style are important for the development of the disease.     

Increasing incidence of diabetes mellitus in Norwegian children 0–14 years of age 1973–1982

Summary 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<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<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<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.     

Epidemiology of human leptospirosis in Trinidad and Tobago, 1996–2007: A retrospective study

A retrospective study to describe the epidemiology of human leptospirosis in Trinidad and Tobago during 1996–2007 was conducted. All confirmed cases of leptospirosis was analyzed according to age, sex, seasonality and geographic distribution. A total of 278 cases were recorded, with an average annual incidence rate of 1.84 per 100,000 population. Seventy-five percent of the cases occurred during the wet season, with the highest number of cases recorded in November. A positive correlation was found between number of cases and rainfall. Males constituted 80% of all cases, and the overall male:female ratio was 4.6:1. The total case fatality rate was 5.8%, with deaths among males four times more common than in females. Clinical leptospirosis was greatest in the 10–19 age group and lowest in the 0–9 age group. The total prevalence was 22 per 100,000 population, with the highest prevalence 41 per 100,000 recorded in the regional corporation of Sangre Grande and the lowest (6 per 100,000) in the city of Port of Spain. The lack of important information and active surveillance showed that the level of awareness of the disease is low in the country. The disease is still under-reported, and is considered to be of significant public health importance.     

Incidence of Type 1 diabetes in children in Cáceres, Spain, during 1988-1999

AIM: To determine the incidence of Type 1 diabetes in Cáceres in children less than 14 years of age. We tested for differences in incidence by age, sex and season at diagnosis. METHODS: All Type 1 diabetes cases with onset <14 years of age between 1988 and 1999 were recorded retrospectively. Pediatric Unit registries provided the primary source of ascertainment. The secondary independent data source was based on the registries of local Diabetic Associations, diabetes camp records and guarantee cards of blood-glucose meters. We used the capture-recapture method for ascertainment. RESULTS: During the 12-year period, 137 new cases of Type 1 diabetes were identified. Completeness of ascertainment was 99.2%. Average annual observed incidence was 16.8/100,000/year (95% C.I. 14.1-19.8). Age-standardised incidence (world population): 16.5/100,000/year (95% C.I. 13.9-19.6). Average annual incidence for 0-4, 5-9 and 10-13-year-old groups: 12.7/100,000 (95% C.I. 8.8-17.9), 18.2/100,000 (95% C.I. 13.7-23.8) and 19.1/100,000 (95% C.I. 14.2-25.1). The highest age-specific annual incidence rate was found in the 10-13-year age group. There was a seasonal onset pattern, with the highest incidence in autumn and winter. November was the month with the highest number of cases (22/137). CONCLUSION: Cáceres has a moderately high incidence of Type 1 diabetes in children less than 14 years of age, similar to that found in other more developed and densely populated regions of Spain, and in the range of other countries of northern Europe. These data do not support the hypothesis of a decrease in the incidence of the disease from north to south over Europe.     

Type 1 diabetes in the Maltese Islands

The prevalence of Type 1 diabetes in Malta was estimated by identifying all cases aged less than 32 years by the end of 1987 who had attended the island's principal diabetic clinic. The age-adjusted prevalence rate for 0-19 year olds was 110.3 per 100,000 (girls 126.2 (n = 65), boys 95.3 (n = 52]. The mean annual incidence, during the period 1980-1987, in 0-19 year olds was 13.3 per 100,000 (n = 113, girls 14.1 and boys 12.6). Males developed Type 1 diabetes 2.1 years later than females (13.7 +/- 6.9 (+/- SD) vs 11.6 +/- 6.7 years). The commonest age of onset was 10 to 14 years. The peak period of onset occurred during the cooler months of November to February. The incidence rates are close to those in Nordic countries and indicate that Type 1 diabetes in Malta is underestimated.     

The epidemiology of diabetes in Swedish children 0–14 years — a six-year prospective study

Summary Since 1 July 1977, all newly diagnosed diabetic children in Sweden aged 0–14 years have been reported to a central register. During the first 6 years, 2300 newly diagnosed diabetic children out of a population of 1.6 million children were registered. The degree of certainty was close to 100%. The mean of the yearly incidence rate for the whole 6 year period was 23.6 per 100000. The prevalence of insulin dependent diabetes mellitus on 1 July 1980 was 1.48 per 1000 and 1.52 on 1 July 1983. Comparing the first and second 3-year periods, an increase was found (22.7–25.1 per 100000). This increase was consistent when analyzing incidence rates by age, sex, and geographical distribution. Cumulative incidence rates revealed a risk of developing diabetes by the age of 15 years of 3.6 per thousand for boys and 3.2 per thousand for girls. The higher incidence for boys was consistent throughout the study period. Seasonal variations in the incidence rate were also consistent, showing yearly incidence peaks in the autumn and winter months. Incidence peaks were noted for both sexes in the pubertal ages. Age- and sex-standardized morbidity ratios varied significantly within the country. 12.8% of the probands had a first degree relative with Type 1 diabetes, and it was twice as common that this relative was a father as a mother. The high and rapidly increasing incidence of Type 1 diabetes in a genetically stable population such as Sweden calls for case-control studies directed towards the identification of environmental pathogens.     

A multicentre study of the prevalence of diabetic peripheral neuropathy in the United Kingdom hospital clinic population

Summary A cross-sectional multicentre study of randomly selected diabetic patients was performed using a standardised questionnaire and examination, to establish the prevalence of peripheral neuropathy in patients attending 118 hospital diabetes clinics in the UK. Vibration perception threshold was performed in two centres to compare with the clinical scoring systems. A total of 6487 diabetic patients were studied, 53.9% male, median age 59 years (range 18– 90 years), 37.4% Type 1 (insulin-dependent) diabetes mellitus, with a median duration of diabetes 8 years (0–62 years). The overall prevalence of neuropathy was 28.5% (27.4– 29.6 %) (95 % confidence interval) in this population. The prevalence in Type 1 diabetic patients was 22.7% (21.0– 24.4 %) and in Type 2 (non-insulin-dependent) diabetic patients it was 32.1 % (30.6–33.6 %). The prevalence of diabetic peripheral neuropathy increased with age, from 5% (3.1– 6.9 %) in the 20–29 year age group to 44.2 % (41.1–47.3 %) in the 70–79 year age group. Neuropathy was associated with duration of diabetes, and was present in 20.8 % (19.1–22.5 %) of patients with diabetes duration less than 5 years and in 36.8 % (34.9–38.7 %) of those with diabetes duration greater than 10 years. Mean vibration perception threshold measured at the great toe was 21.1±13.5 SD volts and correlated with the neuropathy disability score, r=0.8 p<0.001. In conclusion, diabetic peripheral neuropathy is a common complication associated with diabetes. It increases with both age and duration of diabetes, until it is present in more than 50% of Type 2 diabetic patients aged over 60 years. An increased awareness of the high prevalence of peripheral neuropathy, especially in older patients, should result in improved screening programmes in order to reduce the high incidence of neuropathic diabetic foot ulceration.     

The Swedish childhood diabetes study — results from a nine year case register and a one year case-referent study indicating that Type 1 (insulin-dependent) diabetes mellitus is associated with both Type 2 (non-insulin-dependent) diabetes mellitus and autoimmune disorders

Summary From July 1, 1977 to July 1, 1986, 3,503 incident cases of Type 1 (insulin-dependent) diabetes mellitus were registered in the Swedish childhood diabetes study. Using data from this register and from a case-referent study, including all incident Type 1 diabetic children in Sweden during one year and, for each patient, two referent children matched according to age, sex and county, we have studied the associations between Type 1 diabetes and familial Type 1 and Type 2 (non-insulin-dependent) diabetes, thyroid, adrenal, allergic, rheumatic, heart and bowel disease. The mean annual incidence per 100,000 during the nine year period was 25.1 for boys and 23.5 for girls. In 8.5% of the patients, one parent had Type 1 diabetes, 73% of whom were fathers. Fifty-six of the patients (1.7%) had a parent with Type 2 diabetes. The prevalence of parental Type 1 diabetes tended to be higher in patients with younger age at onset; whereas, the opposite was found for patients with parental Type 2 diabetes. In the case-referent study, the age-adjusted odds ratio for Type 1 diabetes when a first and/or second degree relative had Type 1 diabetes was 5.5 (95% confidence limits 4.0–7.7), and in accordance with the findings of the case register, the odds ratio tended to be highest in patients with the youngest age at onset. Season at onset of the patients was not associated with parental Type 1 diabetes. The odds ratio for Type 1 diabetes was significantly increased 3.3 (95% confidence limits: 2.3–4.6) when Type 2 diabetes was reported in relatives (three generations). Odds ratios were also significantly increased (p(0.05) when thyroid or rheumatic diseases were reported among relatives.It is concluded that although the majority of incident Type 1 diabetic children lack family history, parental Type 1 diabetes may influence the age at onset of the disease but has no effect on sex distribution of these children. An increased risk for Type 1 diabetes in children is also indicated when Type 2 diabetes, (non-insulin-treated) thyroid or rheumatic disease is reported in relatives.     

Racial differences in incidence of juvenile-onset Type 1 diabetes: epidemiologic studies in southern California

Summary We have studied the epidemiologic characteristics of insulin-dependent (Type 1) diabetic patients aged 0–19 in a city (San Diego, southern California, USA) characterized by an impressive racial diversity and especially mild and constant climatic conditions. Ascertainment was through retrospective review of medical records in 19 hospitals. For the 3 years 1978–1981 the mean annual incidence of diabetes was 7.3 cases/100,000, with no statistical difference between the sexes. The observed incidence rates in the various ethnic groups was significantly different from expected (p<0.03), with an excess of cases among Caucasians and fewer than expected cases among Mexicans, Blacks and Orientals. There was no identifiable seasonal trend. Some of the clinical char acteristics at diagnosis differed between the sexes: males were slightly older (9.3±5.2 years versus 8.8±3.9 for females), had a shorter duration of diabetes-related symptoms and a higher frequency of infections both at the time of diabetes diagnosis and in preceding months. Females tended to have a higher frequency of Type 1 diabetes in first-degree relatives. This study documents for the first time that, among multiple racial groups living in the same environment, Caucasians are at the highest risk of developing juvenile-onset Type 1 diabetes.     

Epidemiology of type 1 (insulin-dependent) diabetes in Scotland 1968–1976: Evidence of an increasing incidence

Summary A computer file of all Scottish hospital admissions in the period 1968–1976 was searched to identify the 2,505 children (aged < 19 years) with a diagnosis of diabetes. The average annual incidence of the disease (based on first hospital admission) was estimated to be 13.8 per 100,000 children aged < 19 years (boys 14.4 per 100,000; girls 13.2 per 100,000). The highest incidence, 20.0 per 100,000 was in the age group 10–14 years and the lowest 7.1 per 100,000 in those aged < 5 years. It is estimated that during the study period there was an 80% increase in the annual incidence of juvenile diabetes, from about 10 per 100,000 in 1968 to about 18 per 100,000 in 1976. First admission rates showed seasonal variations for those aged 5 years or more, with peaks in October/November and January/February. Marked variation was found in the incidence rates in the different counties of Scotland. The central lowlands which includes the cities of Edinburgh and Glasgow was an area of low incidence. There appeared to be an inverse correlation between the incidence rate in each county and population density. In Glasgow, there was an inverse association between the incidence rate in each city ward and the average number of persons per room. There was no evidence of space-clustering of the disease in different years within the parishes (rural districts) of each county and there was no convincing evidence that the variation in the incidence of diabetes between parishes in the same county was more than might have been expected to arise by chance. The observations are compatible with the disease having a viral aetiology but it is difficult to explain the striking rise in incidence over the study period on this basis.