The Rise of Childhood Type 1 Diabetes in the 20th Century

Edwin A.M. Gale

Disclosures

Diabetes. 2002;51(12) 

In This Article

Incidence Between 1920 and 1950

Insulin changed childhood diabetes from a rare fatal disease to a condition in which prolonged survival was possible, and the medal that the Joslin Clinic minted to commemorate this transformation emphasizes the prevailing uncertainty as to the future of children whose lives depended on insulin. It depicts a small boy and his dog in an open boat with the sun rising beside them, and is entitled "explorers of uncharted seas." Meanwhile, the period between the wars saw great advances in public health and the collection of social statistics. A landmark was the U.S. National Health Survey of 1935-1936. This was a doorstep sampling survey of 2.5 million people living in 700,000 households in 83 cities. The reported rate of diabetes for the age-group under 15 years was 0.35/1,000 for boys and 0.41/1,000 for girls[15]. In contrast, National Health Interview Surveys undertaken later in the century gave prevalence figures of 1.30 and 1.60/1,000 under age 16 years for 1973 and 1976, respectively, with rates (this time up to age 18 years) of 1.30 for both sexes for 1979-1981 and 1.20 for 1989-1992[16].

The main source of incidence and prevalence data for this period is Scandinavia. A Norwegian government survey in 1934, based on a questionnaire to doctors, identified a national total of 253 children under the age of 15 years, giving a minimum prevalence of 0.28/1,000, but ascertainment was undoubtedly incomplete[17]. More detailed information about the incidence of diabetes in Norway is available from two retrospective surveys in Oslo and Bergen. Westlund examined all cases of diabetes admitted to hospital in Oslo over the period 1925-1954. His main aim was to document the effect of food rationing during World War II on the incidence of diabetes (Figure 1), and to do this he needed to establish accurate baseline rates both before and after the war. The assumption was that all cases would be admitted to hospital at diagnosis, and the aim was therefore to identify all first admissions. A total of 4,251 individual patients were identified, and the incidence of diabetes under age 30 years remained relatively constant over the period 1925-1954; the average incidence under the age of 15 years can be estimated as 4.1/100,000/year from the data provided[18].

Incidence of diabetes in Oslo, 1925-1954, per 100,000/year. The rate of onset under the age of 30 years was constant, whereas incidence rates fell rapidly in older age-groups as a consequence of wartime rationing. Redrawn from data in Westlund[18].

Meanwhile, an independent Norwegian survey had been conducted in Bergen. This was then a town of some 100,000 inhabitants with one hospital. Per Hanssen made a heroic effort to identify all cases of the disease over the period 1925-1941. Cases were identified by a retrospective search of hospital admissions from 1910 to 1941 and by examination of a city register established in 1940-1941 to ensure that patients with diabetes received food supplements under wartime conditions. In addition to this, a questionnaire was sent to all doctors in the city asking them to register all cases of diabetes prospectively over a 6-month period beginning March 1941, and death certificates and postmortem reports were also checked for the whole period. This exhaustive search identified 402 patients with diabetes alive in 1941, 46% of whom were receiving insulin and a further 392 who had died over the preceding 16 years. The author concluded that the total prevalence of diabetes had doubled over the 15-year period, but this increase was confined to the older age-groups and, as in the U.S.[19], was attributed to the increasing age of the population. A total of 40 individuals developed diabetes under the age of 20 years, equivalent to an incidence rate (based on the 1934 census) of 7.9/100,000/year for this age-group over the period 1925-1939[17]. Although the confidence intervals around such an estimate will be wide, the overall agreement with the Oslo data is good.

The war also had an indirect impact on Sweden, where, based on ration cards issued in 1942, the State Institute of Human Genetics and Race Biology collected national data on the number of people with diabetes in the population. Ascertainment was checked in Stockholm by a survey of patients receiving hospital treatment over the period 1938-1942, and this identified an additional 14% of patients not receiving ration cards. At that time, the city contained 72 diabetic children under 15 years of age, giving a prevalence of just under 1/1,000[20]. The Pediatric Clinic in Vasterbötten in Northern Sweden retrospectively reported a wartime incidence of 10.2/100,000/year. This estimate is the highest available for the period, and it is therefore of interest that Vasterbötten remained a high incidence area, with rates rising to 37.9/100,000/year by 1973-1977[21].

Finland had a wartime registry of patients receiving insulin or diet supplements, but this was frustratingly incomplete. A national population of 3.64 million was reported to contain 250 individuals under 20 years of age with diabetes, equivalent to a prevalence of 0.2/1,000 for this age-group[22]. The most striking feature of childhood diabetes was its high mortality, reportedly running at ~70 deaths per year. An informal postwar survey in 1953 used a questionnaire addressed to physicians to identify 663 children born since 1939 who had developed diabetes under the age of 14 years, and a further 169 who had died with a diagnosis of diabetes. The mortality rate is exaggerated by under-ascertainment of living cases, but is clearly very high. A more complete subanalysis based on case records from the Children's Clinic in Helsinki showed that a total of 223 children born after 1939 had attended; of these children, 28 (12.6%) had died by 1953. It should not be forgotten that Finland was embroiled in a desperate struggle for survival during the war years, and living conditions must have been very hard. The author estimated the annual incidence of new cases in 1953 at 12.5/100,000/year[23], around one-third of the number affected by the end of the century.

The Finnish experience suggests that consideration must be given to the two main potential reasons for under-ascertainment of childhood-onset diabetes. Contemporary prevalence estimates will be spuriously low where the mortality of childhood diabetes was high, and death with undiagnosed diabetes will lower both incidence and prevalence estimates. The Industrial Department of the Metropolitan Life Insurance Company collected data concerning mortality rates in families of wage-earners in the U.S. and Canada who participated in their insurance scheme[24]. This showed that diabetes mortality in individuals under the age of 20 years fell from 4.1/100,000/year in 1916-1920 to 1.1/100,000/year in 1931-1935, and remained steady until 1945, by which time Joslin was able to comment that "those with onset in childhood have almost ceased to die of diabetes until the duration of the disease has passed twenty years"[25]. Westlund found that only eight children with diabetes had died under 20 years of age in Oslo over the period 1925-1961[26]. This may not be the whole story. The Steno Memorial Hospital in Denmark followed 307 patients diagnosed under the age of 31 years before 1933. Some 3-4% of patients died within 15 years of diagnosis, but almost all of these had presented before age 10 years, the 10-year mortality was 20% in those who lived in country areas, and failure to return for follow-up after the initial visit carried a particularly poor prognosis[27]. Access to medical care was therefore a major factor in survival, and children with diabetes must have fared badly in rural districts or during periods of hardship or social disruption. Joslin remarked in 1927 that "it is the uneducated, untrained, uncared for child in a family with limited resources who is lost"[28], and this chilling comment also applies at the start of the 21st century. A diagnosis of childhood diabetes still carries a death sentence in parts of sub-Saharan Africa.

It is of course likely that some children died with undiagnosed diabetes and did not feature in the incidence or mortality data. Childhood diabetes is still an uncommon condition, and in more recent times, a general practitioner in the U.K. might expect to diagnose three children in a lifetime of practice. Consequently, the diagnosis is often missed at first presentation, especially in the younger age-groups[29]. Early-onset diabetes is nonetheless a progressive and ultimately fatal condition that will eventually force itself upon medical attention. Clinical suspicion has always been the mainstay of diagnosis, even in the AutoAnalyzer era, and we should not assume that earlier generations of physicians, who relied almost totally on their clinical skills, were less gifted or motivated than ourselves. Diabetic ketoacidosis can be diagnosed at a glance, or from the other side of the bed curtain by those with the right olfactory apparatus, confirmation by urine testing was simple and sufficient in symptomatic individuals, and mortality in children was low[30]. It was also a diagnosis worth making. Readers of Lewis Thomas[31] will recall that few effective therapies existed before the introduction of the sulfonamides in 1937. These he lists: liver for pernicious anaemia, thyroid extract for hypothyroidism, vitamin B for pellagra, vaccination or injection of toxin for diphtheria, and not very much else. Insulin was almost the only therapy that could restore a moribund child to healthy normality, thus placing a high premium on successful diagnosis. The number of missed cases will never be known, but in city areas with good access to medical facilities, the great majority were probably diagnosed correctly.

In summary, studies of the incidence and prevalence of childhood diabetes before 1950 underestimate the true frequency of the condition and must be viewed with caution. Access to medical support was variable, but excellent results were achieved at specialized centers and in regions with good organization of health care. The outlook was not as good elsewhere, and prevalence figures will underestimate the true frequency of the condition. It can however be noted that contemporary estimates from Western countries were generally in good agreement with one another and varied little over the period. The most reliable longitudinal study from Oslo applied the same means of ascertainment over 30 years leading up to 1955 and found little variation in the younger age-groups[18]. We therefore need to look later in the century for a major increase in the incidence of childhood diabetes.

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