Objective: The purpose of this study was to identify psychosocial factors associated with glycemic control in a sample of adult women with type 1 or type 2 diabetes mellitus preparing for pregnancy. Methods: This was a cross-sectional study. Participants comprised a subsample (n=38) of a larger study investigating predictors of prepregnancy care uptake in women with pre-existing diabetes. Participants were recruited from the diabetes and pregnancy clinics at 2 major hospitals and completed self-report questionnaires on personality, coping style, social support and knowledge of diabetes and pregnancy. The main outcome was glycemic control using glycated hemoglobin (A1C) as the outcome of interest. Results: The sample was divided into good (n=20) vs. poor (n=18) glycemic control based on their A1C at entry to the study. Univariate tests indicated no differences between the 2 groups on any of the variables except that the good control group were better educated. Hierarchical multiple regression analysis revealed that problem-focused coping and higher education remained significantly associated with better glycemic control when controlling for potential confounds. Conclusions: Providing women with enhanced prepregnancy diabetes education with a particular emphasis on problem-solving and coping skills may enable them to take more proactive approaches to challenges they face in managing their diabetes. That in turn can improve glycemic control at the critical period.