Which Contraceptive Is Best for Women With Diabetes Mellitus?

There is insufficient evidence to determine that hormonal contraceptives do not influence glucose and lipid metabolism in women with diabetes mellitus, concluded a systematic review conducted by the Cochrane Fertility Regulation Group.¹
   
Women with type 1 or type 2 diabetes mellitus should be prescribed a contraceptive that has little to no impact on carbohydrate and lipid metabolism and that has a very low risk profile for microvascular and macrovascular complications. However, it is unknown whether progestogen-only, combined estrogen and progestogen, or nonhormonal contraceptives vary in terms of effectiveness, adverse effects on carbohydrate and lipid metabolism, and long-term effects on micro- and macrovascular disease in women with diabetes mellitus.
   
The researchers identified 4 randomized controlled trials that met inclusion criteria. However, they were unable to combine the data for a meta-analysis because there was too much variability in the contraceptives being studied in the trials, the characteristics of the participants, and the methodological quality. Therefore, the 4 included trials were examined individually.
   
All of the types of contraceptives reviewed were effective in that no unintended pregnancies were reported during the study periods. One trial, the only one with good methodology, compared how a levonorgestrel-releasing intrauterine device (IUD) versus a copper IUD affects carbohydrate metabolism in women with type 1 diabetes mellitus. However, no differences between study groups were found.
   
The other 3 included studies were of limited methodological quality, with 2 comparing progestogen-only pills with various estrogen and progestogen combinations and 1 also comparing levonorgestrel-releasing and copper IUDs. In most regimens, blood glucose levels were stable throughout treatment. However, glucose homeostasis was slightly impaired with high-dose combined oral contraceptives and ethinylestradiol (30 micrograms) plus gestodene (75 micrograms). Conflicting results were noted for lipid levels, with some combined oral contraceptives slightly worsening lipid levels and others slightly improving them. The copper IUD and progestogen-only oral contraceptives also slightly improved lipid levels, whereas the levonorgestrel-releasing IUD had no effect on lipid levels.
   
In the 1 study that included microvascular and macrovascular complications, there was no evidence of thromboembolic incidents or visual disturbances. However, the study duration was short, limiting the value of this finding. These few trials-the methodological quality of which is limited-reveal a need for high-quality trials evaluating intermediate outcomes as well as true clinical endpoints, such as microvascular and macrovascular disease, in women with type 1 or type 2 diabetes mellitus who use combined hormonal, progestogen-only, and nonhormonal contraceptives.

Pertinent Points:
- There is insufficient evidence to assess whether progestogen-only and combined hormonal contraceptives differ from nonhormonal contraceptives in diabetes control, lipid metabolism, and complications.
- Trials that analyze glucose and lipid metabolism and long-term complications for all available contraceptive methods are needed.
 

References:

1. Visser J, Snel M, Van Vlier HAAM. Hormonal versus non-hormonal contraceptives in women with diabetes mellitus type 1 and 2. Cochrane Database Syst Rev. 2013;3:CD003990. doi: 10.1002/14651858.CD003990.pub4.