Contraception and Diabetes

Diabetes raises the risk of congenital malformation, miscarriage, stillbirth and maternal complications when pregnancy occurs with poor glycaemic control, so reliable contraception and planned pregnancy are priorities. Method choice depends on duration, vascular and renal complications, blood pressure, smoking and obesity.

Assessment. Type and duration of diabetes, HbA1c, retinopathy, nephropathy, neuropathy, cardiovascular disease, hypertension, lipids, smoking, BMI, current medicines (ACE inhibitors, angiotensin receptor blockers and statins are teratogenic), and past gestational diabetes.

Uncomplicated diabetes. Diabetes of less than 20 years duration without vascular, renal, retinal or neurological disease.

Complicated diabetes. Diabetes with vascular disease, nephropathy, retinopathy or neuropathy, or of 20 years or more duration.

Gestational diabetes history. A history of gestational diabetes does not restrict any method (category 1) and should prompt postnatal glucose testing.

Effectiveness. First-year pregnancies per 100 women with typical use: implants 0.05, intrauterine devices 0.2 to 0.8, injectables 3, combined pills 8.

Eligibility.

Method comparison. Intrauterine devices and implants are first choice because they have no metabolic effect and the highest effectiveness. Combined pills suit only young, non-smoking patients with short-duration diabetes, normal blood pressure and no complications. DMPA is avoided where vascular disease exists.

Metabolic effects. Progestin-only methods have little effect on glucose control. Combined pills may raise insulin requirement slightly. Neither method delays use of insulin or oral agents.

Special groups. Adolescents with type 1 diabetes can use any method for which they are eligible. Women with diabetes and hypertension follow the more restrictive category. Steroid use and obesity add thrombotic risk with oestrogen.

Regimen lines.

• Copper T 380A: up to 12 years; levonorgestrel 52 mg device: 5 years; insertion within 12 days of the start of bleeding or at any time if reasonably not pregnant; no backup.

• Etonogestrel 68 mg rod: 3 years; levonorgestrel two 75 mg rods: 5 years or 3 years by system; backup 7 days if inserted after day 7 of bleeding.

• Progestin-only pill: one tablet daily without a break; late window 3 hours for the traditional pill, 12 hours for desogestrel and 24 hours for drospirenone; backup 2 days after a late or missed pill.

• DMPA 150 mg intramuscularly every 13 weeks, up to 4 weeks late, or 104 mg subcutaneously every 13 weeks, up to 4 weeks late; only in uncomplicated diabetes.

• Combined pill with ethinylestradiol 30 micrograms and levonorgestrel 150 micrograms daily for 21 days, then a 7-day break: only in uncomplicated diabetes, non-smokers under 35 years with normal blood pressure.

Preconception. Aim for the lowest HbA1c that avoids hypoglycaemia before stopping contraception, stop teratogenic medicines, switch to insulin or metformin as appropriate, screen for retinopathy and nephropathy, and give folic acid 5 mg daily before conception.

Follow up. Review glycaemic control, blood pressure, weight and complications at each visit; reassess the method when complications develop.

New complications on a method. If vascular disease, nephropathy or retinopathy develops on a combined method, stop it and switch; on DMPA, switch to an implant or intrauterine device.

Bleeding. Treat bothersome progestin-related bleeding with ibuprofen 800 mg three times daily for 5 days if renal function is normal, otherwise with tranexamic acid dose-reduced to kidney function; avoid combined pills in complicated diabetes.

Pregnancy on a method. Refer urgently for specialist antenatal care and medicine review.

Red flags. Ketoacidosis, recurrent hypoglycaemia, leg swelling, chest pain, visual change.

Referral and escalation. Refer complicated diabetes, pregnancy planning, hypertension and new vascular events to the diabetes team.