Background : Prior studies have shown an association between preeclampsia and increased levels of plasma insulin. The present study was conducted to compare the changes in fasting plasma insulin levels in pre-eclamptic women with normal controls during pregnancy.

Materials and methods : In a nested case-control study, 674 parturients, with normal blood pressure in the 20^th gestational week, were followed through the second and third trimesters. Blood samples were obtained from 16 healthy and 16 preeclamptic women during the second and third trimesters to compare their insulin and glucose levels. Groups were matched according to age, parity, gestational age, and body mass index.

Results : The fasting insulin levels increased from 15.3±1.3μIu/ml to 25.3±1.4, between 2^nd and 3^rd trimesters in pre-eclamptic women (p<0.01) and from 10.4±0.9 to 16.2±1.3 μIu/ml in the control group (p<0.01). Fasting insulin level and its mean changes during the course of pregnancy were higher in preeclamptic women as compared to controls (p<0.01), whereas, there was no significant change in glucose levels during pregnancy in either group.

Conclusion : Women who develop preeclampsia have higher insulin levels before the clinical evidence of disease than women who remain normotensive during pregnancy and this may increase further during the disease course. These changes may be in association with insulin resistance in Na transport mechanism of cell membrane.