Basal insulin requirements after progesterone treatment in a type 1 diabetic pregnant woman

We herein report the case of a 37-year-old type 1 diabetic pregnant woman treated with an insulin pump. Although the patient's glycemic control deteriorated following progesterone treatment for the prevention of preterm delivery and miscarriage, it was improved by adjusting the basal insulin rate on the days of progesterone treatment. Excess progesterone is known to impair both insulin sensitivity and secretion. The present case is the first report to evaluate deterioration of glycemic control induced by progesterone treatment and to determine the dose of insulin required in a type 1 diabetic pregnant woman whose insulin secretion was completely depleted.