Effect of a levonorgestrel intrauterine system on women with type 1 diabetes: a randomized trial

Women with diabetes need safe, effective contraception. Although intrauterine devices provide superior contraception, concerns remain that progestin absorbed systemically from the levonorgestrel-releasing device may impair carbohydrate metabolism. To examine the effect of the levonorgestrel-releasing intrauterine system on glucose metabolism in diabetic women.

We randomly assigned 62 women with uncomplicated insulin-dependent diabetes mellitus to either a levonorgestrel-releasing or a copper T 380A intrauterine device. The primary outcome to assess glucose metabolism was glycosylated hemoglobin; fasting serum-glucose levels and daily insulin dose requirements over 12 months of observation were examined as well.

Outcome data were available for 29 women using the levonorgestrel-releasing and 30 using the copper device. At 12 months, mean glycosylated levels were similar for women of the 2 groups (6.3%, standard deviation [SD] +/- 1.5 compared with 6.3%, SD +/- 1.3, respectively). The same was true for mean fasting-serum glucose levels (7.4 mM, SD +/- 4.2 compared with 7.5 mM, SD +/- 4.2) and daily insulin doses (35.1 units, SD +/- 12.8 compared with 36.4 units, SD +/- 9.0). No important differences were noted at either 6 weeks or 6 months.

The levonorgestrel-releasing device had no adverse effect on glucose metabolism, even at the 6-week observation when systemic levels of levonorgestrel would have been higher than at later observations. Concern about a potential adverse effect of this contraceptive on glucose control is unwarranted, and its use in women with diabetes should be liberalized.

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