Where does IDF get its information from for the statistics found within the Diabetes Atlas?
IDF gathers information from peer-reviewed journals, national health statistics reports, reports from international agencies such as the WHO and CDC, and from personal communication with investigators within the IDF network. These studies are then judged for quality and used to generate the estimates for diabetes found in the Diabetes Atlas. Estimates for mortality and healthcare expenditures rely on these day and other published figures to the estimate the number of deaths and the medical costs attributable to diabetes.
When should I use national prevalence and how is this calculated?
The national prevalence is a percentage of the number of adults (20 – 79 years) who have diabetes in the given year (either 2011 or 2030) in a country or region. It is calculated by taking the number of cases in adults and dividing by the total population in adults. The national prevalence should be used when reporting statistics for just one country or region, or when the statistics being reported are not for comparison. If you are comparing one country or region to another, you should use the comparative prevalence.
When should I use comparative prevalence and how is this calculated?
The comparative prevalence allows us to adjust for the fact that there are different proportions of young and old people in different countries. In order to compare these countries, we take the national prevalence and make an adjustment to estimate what the prevalence would be for that country if the distribution of the population in different ages were different. The distribution that is used for this calculation is applied to all countries in the same way and is based on a distribution developed by the WHO in order to compare the relative burden of diseases in different countries.
What factors does IDF take into account when calculating the Atlas 2030 projections?
For projections, we only use changes in the predicted population and urbanization changes available from the UN Population Division. We do not include any predictions for changes in obesity or other risk factors. The projections are therefore quite conservative.
Are undiagnosed cases part of the number of cases for 2011 or in addition to?
Undiagnosed cases are already included in the total number of cases reported.
I notice that some of the national prevalence country data is less than the 4th edition of the Atlas. Why is this?
The numbers of cases in a country or the prevalence may have decreased from previous editions because of changes to the methodology that makes the estimates more precise. In the past, estimates for the proportion of undiagnosed diabetes as well as the ratio of cases in urban settings to rural settings were based on an average of many countries. With the new methodology we are able to make these estimates more precise and driven by evidence found in studies. In some cases those estimates were lower than those used for the 4th edition. The source data for those estimates is likely the same as the one used for the previous edition/
If the prevalence rates in some countries have decreased since 2011, how can IDF say that diabetes is on the increase?
Looking at studies in the same country over several years there is no country which shows a decrease in diabetes. Every country with data on multiple years shows a consistent increase. Our estimates may have decreased in some countries because we were able to make some of our assumptions more precise and driven by data in new studies than in previous editions. Thus, actual numbers may change slightly but the overall trend is increasing for all countries.
What are the main factors, according to the Atlas, driving the diabetes epidemic?
There are a number of factors driving the diabetes epidemic but the most significant are those associated with type 2 diabetes: poor diet, more sedentary lifestyles, and increases in life expectancy. We also note a increase in type 1 diabetes in children although the causes of this are still being investigated, links have been found to environmental factors, trends in certain viruses, and early dietary habits.
How does IDF propose we start to tackle this epidemic?
IDF has released a Global Diabetes Plan which outlines policies that will go far in preventing new cases of diabetes, providing good care to those with the diseases, and reducing the discrimination faced by those with diabetes. Countries must demonstrate their commitment to turning the tide on diabetes by implementing these policies across many sectors.
Where and how does IGT fit into pre-diabetes?
Pre-diabetes is characterized by a number of problems in a person’s ability to process sugar in the blood, among them an impairment in the ability to use glucose, or impaired glucose tolerance (IGT). Studies have shown that IGT is powerful risk factor for type 2 diabetes and many consider it to be a transition phase to diabetes. There is also a significant cardiovascular risk associated with having IGT which means that even if people with IGT never go on to develop type 2 diabetes, it is still important that they get good care and education.
Why in regions such as the Middle East and North Africa are there low levels of IGT but high cases of diabetes?
We are still discovering why some populations with a high prevalence of diabetes have a low prevalence of IGT and vice versa. It is possible that for regions like MENA, where diabetes is rapidly increasing, the relatively low prevalence of IGT reflects a rapid transition from normal glucose tolerance to diabetes. Thus, people there may not spend much time in an impaired glucose tolerance state before transitioning to diabetes. More research is needed to understand these differences.
Why are there no prevalence estimates for type 1 diabetes in adults?
The majority of the sources reporting type 1 diabetes in adults do not distinguish between type 1 and type 2 diabetes, which makes it difficult for the IDF Diabetes Atlas estimates to make that distinction.