Friday May 29 2009
The number of children with type 1 diabetes is on the rise
“The increasing popularity of Caesarean births and having children later in life are contributing to a dramatic rise in cases of diabetes in young children,” the Daily Mail reported. The newspaper said that “the number of children under five with type 1 diabetes is likely to double by 2020”. It said that modern lifestyles, children being born to older mothers, caesarean sections and reduced exposure to germs are all contributing factors.
The Europe-wide study behind these reports found that new cases of type 1 diabetes are increasing annually by an average of 3.9% a year. If the trend continues, there will be a substantial increase in the number of children with the condition, from an estimated 15,000 new cases a year in 2005 to 24,400 in 2020.
Importantly, studies like this cannot establish the reasons behind this increase. The researchers speculate that lifestyle factors, such as caesarean sections, the age of the mother and rapid weight gain early in life, may play a role. However, this is speculation. One of the lead researchers said, “currently none of these risk factors can be said to be responsible for the increase, the cause of which remains largely unknown”.
Where did the story come from?
The research was carried out by Dr Christopher C Patterson and members of the EURODIAB study group with representation from Queen’s University Belfast and other academic and medical institutions across Europe. The study was supported in part by the European Community Concerted Action Program grants and was published in the peer-reviewed medical journal The Lancet.
What kind of scientific study was this?
The researchers say that the number of children under 15 being diagnosed with type 1 diabetes is increasing. They say that predicting the number of children with diabetes in the future will enable the planning and preparation of adequate care.
In this study, the researchers examined trends in the number of new cases of type 1 diabetes in children under 15 across Europe. They looked at the period between 1989 and 2003.
From registries in 20 centres across 17 countries, the total number of reported new cases of type 1 diabetes was estimated at 29,311. Most of the centres obtained their data on new cases either from hospital records or by being notified by paediatricians or family doctors. The number of new cases of type 1 diabetes a year was then determined. A process called standardisation was applied to the figures, which essentially converts country rates into values that can be compared with each other.
The centres’ accuracy at recording new cases was also estimated to reflect how reliable the data were. Statistical methods were used to investigate the changes in number of new cases over time while taking into account the changes in population numbers and structure. The researchers also used statistical models to predict the number of cases expected in the different age groups in 2020.
What were the results of the study?
There were increases in the incidence of type 1 diabetes across most of the European countries, ranging from 9.3% a year increase in Poland to 1.3% in Norway. These increases were statistically significant across all countries except for two: Spain and Luxembourg. The average increase across all 20 centres was 3.9% a year, with the highest increase in the 0-4-year-old age group (5.4%).
Modelling suggested that the total number across these countries would increase from 94,000 cases in 2005 to 160,000 cases in 2020.
The researchers estimate that the number of new cases in Europe in 2005 was 15,000, of which 24% were 0-4 years, 35% were 5-9 years and 41% were 10-14 years.
They predict that in 2020, the number of new cases will be 24,400. This estimate predicts a doubling in numbers in children younger than five years and a more even distribution across age groups than at present (29% in 0-4 year-olds, 37% in 5-9 year-olds and 34% in 10-14 year-olds).
What interpretations did the researchers draw from these results?
The researchers say that if present trends continue there will be a doubling of new cases of type 1 diabetes in European children younger than five years between 2005 and 2020. They say there will be a 70% increase in the total number of cases in young people under 15 years old.
What does the NHS Knowledge Service make of this study?
This time-trend and modelling study has demonstrated that new cases of type 1 diabetes are increasing across most European countries studied. If this trend continues, the number of new cases in children under five will double between 2005 and 2020. There are several points to bear in mind when interpreting the results of this research:
- This is a well conducted study that took into account the completeness of the records used to make these predictions. With the methods that were used, all centres in all countries had over 90% completeness. This means that the estimates of incidence for these countries are likely to be robust.
- Importantly, time-trend studies such as this are not set up to explore the reasons behind changes in the number of new cases. The researchers explicitly state that their analysis “gives no explanation for the time trends” described. The coverage of this research in some of the newspapers appears to suggest that research has definitively linked these increases in type 1 diabetes to caesarean sections and mother’s age. This is not the case. BBC News quotes one of the researchers as saying that some lifestyle factors, including older mothers, caesarean section and children with rapid weight gain in early life may increase the risk of type 1 diabetes, but that, “currently none of these risk factors can be said to be responsible for the increase, the cause of which remains largely unknown”. Lifestyle may be contributing to the increase, but these remain “possible environmental factors” that need further investigating.
- Changes in the prevalence of the genes thought to contribute to type 1 diabetes is an unlikely cause because the increase has been observed rapidly in less than one generation.
There are no effective means of preventing type 1 diabetes and given this predicted increase, the researchers’ concluding message is an important one: adequate healthcare resources should be made available to meet these children’s needs.