Intrauterine contraceptive devices in diabetic women

11 of 30 (36.6%) insulin-dependent diabetic women fitted with intrauterine contraceptive devices (IUCDs) became pregnant within 1 year, whereas the pregnancy rate for non-diabetic women fitted with the same types of IUCD by the same consultant gynaecologists over a similar time period was 4 per 100 women years (4%). As soon as the high risk was recognised, devices were removed (2 from diabetic women who were pregnant and 19 from non-pregnant diabetic women), and patients were advised about other methods of contraception. The IUCDs were examined in a scanning electron microscope with X-ray microprobe analysis to measure the amount of copper eroded from the wire, the extent of the encrustation (if any) deposited on the wire, and the composition of the deposit, and the data were compared with those for 111 devices removed from non-diabetic women, 40% of the IUCDs from diabetic women had sulphur and chloride in the deposit, compared with 15.3% of IUCDs from normal women, and fewer IUCDs from diabetic women had calcareous deposits. In devices from normal women, erosion and deposition seemed to occur independently, but in IUCDs from diabetic women, there was high erosion, there were also large deposits, and where there was little deposit, the erosion was slight. 7 of 14 IUCDs taken from normal women who had become pregnant with an IUCD in situ had a high sulphur plus chloride deposit; none of these IUCDs had a predominantly calcareous deposit compared with 19.8% of the IUCDs from non-pregnant normal women. The evidence militates against the insertion of IUCDs in diabetic patients and indicated that, even in non-diabetic women, there may be small groups for whom the risk of becoming pregnant is very high.