Weight reduction, diet, exercise and behavioral therapy advised / strength of the recommendation varies
On 10th July 2012, the German Institute for Quality and Efficiency in Health Care (IQWiG) published the results of a literature search for evidence-based guidelines for the treatment of obesity in type 2 diabetes. The aim of the report was to identify those recommendations from current guidelines of high methodological quality that may be relevant for a possible new obesity module in the disease management programme (DMP) for type 2 diabetes.
Diet, exercise and behavioural therapy generally advised
IQWiG found that the recommendations of the various guidelines for the treatment of people with type 2 diabetes who are also grossly overweight were more or less consistent: in general, alongside weight reduction, diet, exercise and behavioural therapy were also advised. Above a certain Body Mass Index (BMI), some guidelines also mention drugs to aid weight reduction (BMI ≥ 27 kg/m²) or surgery – for example a gastric bypass (BMI ≥ 35 kg/m²) – as a treatment option. However, the strength of the recommendation, i.e. whether the particular intervention “could”, “should” or “must” be used, varies between the individual guidelines. The level of evidence, i.e. the extent to which the recommendations are backed up by results from studies, also differs.
Systematic reviews do not report patient-relevant outcomes
In accordance with the commission received from the Federal Joint Committee (G-BA), the Institute searched for and evaluated systematic reviews, as well as guidelines. The aim was to compare the recommendations of the guidelines with the conclusions of the reviews, i.e. the scientific evidence from studies. However, IQWiG was unable to identify any reviews that were based on the results of studies of high methodological quality and summarized the relevant results for the treatment of people who suffered from both type 2 diabetes and obesity.
Furthermore, the systematic reviews reported largely metabolic parameters, but no patient-relevant outcomes such as blindness or amputation. This means that the conclusions in the guidelines are, for the most part, not supported by evidence from systematic reviews.
Procedure of report production
IQWiG published the preliminary results in the form of the preliminary report in October 2011 and interested parties were invited to submit comments. When the commenting procedure ended, the preliminary report was revised and sent as a final report to the contracting agency, the Federal Joint Committee, in May 2012. The written comments are published in a separate document at the same time as the final report. The report was produced in collaboration with external experts.