Acute cataract is recognized as a rare complication in adolescents with type 1 diabetes mellitus and may be associated with rapid improvement in glycaemia in patients with newly diagnosed diabetes. Transient cataracts, which resolve following improved metabolic control, and irreversible cataracts requiring surgery have also previously been documented. Development or progression of retinopathy may complicate pregnancy in women with diabetes. To our knowledge, we present the first case report of an acute cataract developing postpartum in a woman with type 1 diabetes. This rare case serves to demonstrate a possible association between acute cataract and altered glycaemic control in pregnancy. Acute cataract should be considered in any woman with diabetes who develops sudden visual loss following pregnancy.