Regardless of the screening criteria used, multiple reports demonstrate that performance of post-partum screening for those with a GDM history has been the exception, rather than the rule (72, 74, 75, 79-81). While performance of screening has improved over the past decade, almost half of women with a GDM history do not undergo screening of any kind or undergo screening with tests such as glycosylated hemoglobins (75, 82). The latter tests are not recommended as screening tests due to relatively decreased sensitivity and specificity (69).
Reasons why women forego screening are speculative but include women's low perception of diabetes risk (83), lack of healthcare provider perception of risk (84, 85), and lack of other steps necessary for screening such as lab slip distribution or test ordering (84, 86). The reasons why women forego screening may also differ between study populations. Russell et al. found that screened and unscreened women had similar glucose levels during pregnancy (80), but screened women were more likely to attend the postpartum visit, suggesting that barriers to the postpartum visit also presented barriers to screening. In contrast, Smirnakis et al. found that screened women had more favorable fasting and 1-h glucose values from the index GDM diagnosis (79). Even though many women were not screened, greater than 90% attended a postpartum visit, suggesting that lower risk during pregnancy influenced rates of return after pregnancy rather than postpartum visit barriers in that health system.
Quality improvement studies on this topic are few. Hunt and Conway noted that screening performance improved with nurse case-management (74), including mailed reminders, telephone calls and home visits. We are not aware of other interventions aimed at improving postpartum screening. Infrequent postpartum screening leads to missed diagnoses of postpartum glucose intolerance. In addition, low performance of postpartum screening could bias estimates of future diabetes risk if screened women were different than unscreened women. In a systematic review of studies examining conversion to type 2 diabetes, Nicholson et al. found that 75% of studies included reported a loss to follow-up greater than 20% (87).
In particular, retrospective cohorts including only women who have undergone the postpartum test might misrepresent risk. If women who were not screened were at lower or higher risk than women who were screened, this would overestimate and underestimate diabetes risk estimates, respectively. Indeed, women who are not screened may have greater prevalence of risk factors for diabetes, including elevated glucose levels (74, 79), prior macrosomia (72), poorer education (75), obesity (75) and macrosomia with the current pregnancy(75).
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