Prevention and reversal of glycogen infiltration in the pancreatic islets of fetuses from diabetic rats

Abstract

Fetuses removed by Caesarean section (between days 17 and 21 of pregnancy) were compared with litter-mates removed at autopsy (between days 21 and 23).In one diabetic group, all rats were treated with a large dose of insulin until Caesarean section when insulin treatment was stopped. No fetuses removed by Caesarean section showed glycogen infiltration when blood sugar was less than 240 mg/100 ml. At autopsy, glycogen appeared in all fetuses from mothers which had blood sugar levels above 240 mg/100 ml for two days or longer; no glycogen appeared in fetuses from mothers which had blood sugar levels below 240 mg/100 ml.In another diabetic group, all rats were treated with insulin, but the insulin dose was increased immediately after Caesarean section. All fetuses removed by Caesarean section showed glycogen infiltration when the blood sugar level was greater than 240 mg/100 ml. At autopsy, glycogen had disappeared in fetuses from mothers which had blood sugar levels less than 240 mg/100 ml for 2 to 3 days; glycogen persisted in fetuses from mothers which had blood sugar levels above 240 mg/100 ml.It is concluded that glycogen appears in fetal islets if blood sugar level is greater than 240 mg/100 ml for two days or longer. This change is both preventable and reversible and is influenced by the level of blood sugar and by the duration of hyperglycemia.