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

Edwin A.M. Gale

Disclosures

Diabetes. 2002;51(12) 

In This Article

Incidence Trends Over the Past 40 Years

More rigorous epidemiological methods came into use in the second half of the century, but reliable data remain scanty for the period 1950-1975, and the rising incidence of the condition was not widely recognized until the 1980s[49]. Several of the more useful earlier sources have already been considered. A systematic review considered incidence trends spanning the period 1960-1996 and noted that a significant rise in incidence was recorded for 24 of 37 longitudinal studies from 27 countries, with a similar trend in a further 12; only 1 reported a small decline. The average annual increase was 3.0% (95% CI 2.6-3.3), with a greater relative increase in lower-incidence countries. Extrapolation of these trends indicated that the global incidence of type 1 diabetes would increase by 40% over the period 1998-2010[1]. In line with this, a large European survey for the period 1989-1998 showed a 3.2% (95% CI 2.7-3.7) annual increase, most marked in some Central and Eastern European countries[2]. In absolute terms, the increase is similar in the age bands 0-4, 5-9, and 10-14 years, but the most rapid increase relative to baseline was seen in the youngest age-group[50,51]. The U.S. stood apart from other parts of the world in reporting a stable incidence of childhood type 1 diabetes over much of this period[52], but a rapid increase was noted in the Allegheny County population over the period 1985-1989, with an overall increase of 83% for the period 1966-1989. The most rapid increase was noted in nonwhite males and in the 0-4 year age-group[53]. The existing capability to monitor the frequency of this condition in the U.S. is limited[52], and the observation that Canada has the third highest rate in the world[54] suggests that North America has not escaped the pandemic of childhood type 1 diabetes.

In summary, the rise in childhood diabetes can be traced back to the middle of the 20th century. Although it is important not to overinterpret limited data, there is some suggestion that a rising incidence first became apparent in those countries with the highest current rates of diabetes and reached lower incidence populations in a later, staggered fashion. Consistent with this, the relative rate of increase is inversely proportional to current incidence[1], suggesting a catch-up phenomenon. The overall impression from combined analysis of many studies is a linear increase, but a saw-tooth pattern often makes interpretation of shorter-term changes uncertain in individual populations. Tuomilehto et al.[41] pointed out that an incidence of 200-300 new cases per year is required to detect an annual increase of 2% with any degree of reliability. It is therefore of note that Norway, with a population large enough to meet this qualification, has shown no increase at all over the past decade[36]. A similar effect has recently been reported from other high-incidence areas, Finland excepted[2]. It would be premature to conclude that this represents a genuine plateau, but it seems likely that a new equilibrium will eventually be established in most populations. In the interim, a continued linear increase seems inevitable in most parts of the world.

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