TY - JOUR
T1 - Carbohydrate metabolism in pregnancy
T2 - XIII. relationships between plasma insulin and proinsulin during late pregnancy in normal and diabetic subjects
AU - Phelps, Richard L.
AU - Bergenstal, Richard
AU - Freinkel, Norbert
AU - Rubenstein, Arthur H.
AU - Metzger, Boyd E.
AU - Mako, Mary
PY - 1975/12
Y1 - 1975/12
N2 - To assess the effects of pregnancy on the relationships between plasma insulin and proinsulin, studies were performed during late gestation in women with normal carbohydrate metabolism or diabetes mellirus. Plasma was secured after overnight fast and 1, 2, and 3 hours following oral glucose (100 g). Samples were analyzed directly for total immunoreactive insulin (TIR) and for insulin and proinsulin following plasma fractionation by gel filtration. Fractionation disclosed that most of the normal gestational increase in basal and glucosestimulated TIR can be ascribed to insulin rather than disproportionate increments in proinsulin-like components. Normal proinsulin/insulin relationships were also preserved in mild diabetics despite greater variability in their TIR response to glucose. Thus, mild carbohydrate intolerance during pregnancy is not attended by abnormalities in plasma proinsulin. In contrast, basal proinsulin levels were elevated in 4 of 9 pregnant subjects with diabetes sufficiently severe to necessitate subsequent insulin therapy. Following glucose administration in the severe diabetics, the relative contribution from proinsulin to TIR was altered so that ratios of circulating proinsulin/insulin were increased at all levels of blood sugar. Postpartum tests of glucose tolerance in some of the normal and mildly diabetic subjects confirmed that pregnancy per se does not modify appreciably the relationships between plasma insulin and proinsulin although there may be some tendency for proinsulin to account for a smaller proportion of TIR.
AB - To assess the effects of pregnancy on the relationships between plasma insulin and proinsulin, studies were performed during late gestation in women with normal carbohydrate metabolism or diabetes mellirus. Plasma was secured after overnight fast and 1, 2, and 3 hours following oral glucose (100 g). Samples were analyzed directly for total immunoreactive insulin (TIR) and for insulin and proinsulin following plasma fractionation by gel filtration. Fractionation disclosed that most of the normal gestational increase in basal and glucosestimulated TIR can be ascribed to insulin rather than disproportionate increments in proinsulin-like components. Normal proinsulin/insulin relationships were also preserved in mild diabetics despite greater variability in their TIR response to glucose. Thus, mild carbohydrate intolerance during pregnancy is not attended by abnormalities in plasma proinsulin. In contrast, basal proinsulin levels were elevated in 4 of 9 pregnant subjects with diabetes sufficiently severe to necessitate subsequent insulin therapy. Following glucose administration in the severe diabetics, the relative contribution from proinsulin to TIR was altered so that ratios of circulating proinsulin/insulin were increased at all levels of blood sugar. Postpartum tests of glucose tolerance in some of the normal and mildly diabetic subjects confirmed that pregnancy per se does not modify appreciably the relationships between plasma insulin and proinsulin although there may be some tendency for proinsulin to account for a smaller proportion of TIR.
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U2 - 10.1210/jcem-41-6-1085
DO - 10.1210/jcem-41-6-1085
M3 - Article
C2 - 1107346
AN - SCOPUS:0016677965
VL - 41
SP - 1085
EP - 1091
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
SN - 0021-972X
IS - 6
ER -