Based on strong evidence that hyperglycemia is harmful to the fetus, guidelines recommend strict diabetes regulation during pregnancy, but the rate of severe hypoglycemia is four times the rate before pregnancy (1). A newly developed tool of continuous glucose monitoring with display and alarm might be helpful in reducing the risk of recurrent episodes of severe hypoglycemia during pregnancy.
A 32-year-old woman with a history of diabetes for 21 years experienced 18 episodes of severe hypoglycemia the year preceding pregnancy, despite treatment with an insulin pump, frequent home blood glucose measurements, and HbA1c (A1C) ∼7.5%. Episodes of severe hypoglycemia were prospectively recorded from gestational week 7. Three 24-h home blood glucose measurements (eight-point profiles), A1C, and insulin dose were registered prospectively at gestational week 7, 14, 22, 27, and 33.
Between 7 and 16 weeks of gestation, the patient experienced seven episodes of severe hypoglycemia without any obvious explanations of the events. Treatment was intramuscular glucagon in four cases and juice in the remaining three. Mean blood glucose was 1.5 mmol/l (range 1.0–1.9). Based on this experience, continuous glucose monitoring with a display and programmed to alarm at glucose values <4.0 mmol/l was introduced at gestational week 17 (Guardian; Medtronic Minimed, Northridge, CA) (2).
During pregnancy, mean blood glucose remained stable between 6 and 8 mmol/l and A1C declined from 6.7 to 6.2%. Insulin dose was 45 IE before pregnancy and 43 IE at week 33. After the Guardian was introduced, the patient only experienced one episode of severe hypoglycemia at gestational week 19 at night while the Guardian was out of function.
The observed glucose values below 2.2 mmol/l were eliminated. Spontaneous rupture of membranes occurred at gestational week 36, and a healthy baby of 2,982 g was born. The woman continued carrying the device with no hypoglycemic events for 3 months after delivery.
Introduction of a Guardian at gestational week 17 led to a dramatic decrease in the occurrence of episodes of severe hypoglycemia from 1.5 episodes/month to 0.3 episodes/month in the remaining part of pregnancy in combination with a decline in A1C to 6.2%. The device was well tolerated by the patient. Limitations of the Guardian are the <100% safety and accuracy of the device (2). In addition, three daily calibrations are required.
A Guardian might be a helpful tool in pregnant patients with type 1 diabetes who are susceptible to frequent episodes of severe hypoglycemia. Also, nonpregnant patients with type 1 diabetes and hypoglycemia unawareness might benefit from a Guardian. Frequent severe hypoglycemic events are expensive from a socioeconomic point of view, and the cost-effectiveness using a Guardian would be of interest to evaluate in the future.
