[Heterogeneity of insulin resistance level in gestational diabetes mellitus. Therapeutic implications]

The evaluation of insulin resistance (IR) level in population of women with gestational diabetes(GDM) and its relation to treatment of GDM.

657 GDM women, aged 17-45, treated between the years 2003 and 2005, in Bydgoszcz were studied. Age, pregravid body mass index(BMI), weight gain during pregnancy at the GDM diagnosis, week of GDM diagnosis, week of the beginning of insulin therapy and daily doses of insulin were assessed in the whole population. Daily doses of insulin were evaluated as minimal doses needed at the initial phase of GDM therapy and as maximal doses during gestation. IR was evaluated at the GDM diagnosis, with the use of homeostasis model assessment (HOMA-IR), based on fasting glucose and insulin concentration.

47% women were classified as low HOMA-IR(<2) subpopulation, 50% as intermediate HOMA-IR(2-10) subpopulation, 3% as high HOMA-IR(10-46)subpopulation. Subpopulation with intermediate HOMA-IR had higher BMI, higher weight gain and blood glucose at 0 OGTT compared to subpopulation with low HOMA-IR but lower insulin concentration compared to high HOMA-IR subpopulation. Women in high HOMA-IR subpopulation and in intermediate HOMA-IR subpopulation were twice as often treated with insulin, compared to low HOMA-IR group, accordingly, 58%, 42%, 24%. Daily insulin doses, assessed both minimal and maximal doses, were increasing parallel to HOMA-IR in whole population, accordingly, minimal doses of insulin, 16.0 = -12.7 vs 18.4 vs 20.8 vs 30.8 +/- 30.3 and maximal doses of insulin, accordingly, 39.0 +/- 322.4 vs 50.9 +/- 42.4 vs 70.3 +/- 30.3.

The studied population of women consisted mainly of subpopulation with low or intermediate HOMA-IR value, in rare cases, of high HOMA-IR value. Our results suggest that adipose tissue is particularly associated with insulin resistance level in subpopulation with intermediate HOMA-IR. Both, frequency of insulin therapy and daily insulin doses are associated with insulin resistance level at the GDM diagnosis.