Strengths and limitations
GDM
MINOR, EVENT, GDM, SECONDARY, TYPE 2 DIABETES MELLITUS
The simple study design, with its adaptation to existing system resources, ensured the inclusion of practically all cases and high follow-up rates. The validity of the Danish National Patient Register database enabled the identification of women with a GDM diagnosis, lending strong support to our expectation that women receiving this diagnosis through ICD-10 coding during pregnancy/childbirth are correct [To ensure the long-term sustainability of the reminder intervention, we included women who had been screened in the previous 12 months. Any negative consequences of receiving an irrelevant reminder were limited by encouraging the women to disregard it, but more knowledge of women’s perspectives on receiving the reminder is, however, needed to ensure that no significant harms were associated with this study. The results of a qualitative study of this are forthcoming.In the assessment of the primary outcome, several data sources were used to secure identification of an event which according to recommendations could include three different blood tests. However, in relation to the secondary outcome, ICD-10 coding fails to securely identify those who are merely diagnosed and treated for type 2 diabetes mellitus in general practice [Our subgroup analysis contributes to the discussion of the design of future electronic reminder systems, but its results should be interpreted with caution as the numbers were small and randomization may not have been maintained in the subgroups. Moreover, knowledge of insulin therapy rates during pregnancy with GDM should be classified, as it can affect women's motivation to participate in screening. Nevertheless, the RCT design is expected to have distributed the number of women who have received insulin therapy during pregnancy equally between the control and the intervention group.Informing GPs about the study before despatching the reminder may have increased uptake of screening in the control group, which may have resulted in an underestimation of the effect of the reminder. However, we believe this would have had a minor effect as GPs properly are inundated by information, and that the reminder was addressed to women.