Diabetes in pregnancy becoming more common in women with HIV in UK and Ireland

The frequency of diabetes during pregnancy is rising in women with HIV in the United Kingdom and Ireland, in line with trends in the rest of the population, Laurette Bukasa of University College London reported at the British HIV Association conference last week in Gateshead.

The study also found that the proportion of women diagnosed with high blood pressure during pregnancy has not risen.

Blood sugar levels can rise during pregnancy, leading to the development of diabetes. Women are at higher risk of gestational diabetes if they are overweight or have obesity, have a South Asian, Black or African Caribbean or Middle Eastern background, or if a close family member has had diabetes. Having HIV does not raise the risk of developing gestational diabetes, but protease inhibitor-based antiretroviral treatment may raise the risk if it is started early in pregnancy.

A recently published study of pregnancies in South Africa’s Western Cape province found that women with HIV on antiretroviral treatment before conceiving had a lower risk of developing high blood pressure during pregnancy than women without HIV.

The UK study looked at the prevalence of diabetes and high blood pressure during pregnancy in women with HIV in the United Kingdom and Ireland between January 2010 and December 2020. The study also looked at the relationship between gestational diabetes and hypertension and adverse pregnancy outcomes including stillbirth, pre-term birth and low birth weight.

The study evaluated 10,401 pregnancies in 8998 women with HIV; 1104 pregnancies were excluded from the analysis either because HIV was diagnosed during pregnancy or because delivery occurred prior to 24 weeks (either miscarriage or very pre-term birth). The annual number of pregnancies in women with HIV halved between 2010 and 2020, from just under 1300 a year to approximately 600 a year in 2020.

Women were screened for gestational diabetes between weeks 24 and 28 of pregnancy if they had a body mass index of 30 kg/m2 or above, a previous baby with a high birth weight, a family history of diabetes, or belonged to a minority ethnic group with a high prevalence of diabetes.

Diabetes was diagnosed during 554 pregnancies in 503 women; in 511 cases this was defined as gestational diabetes.

High blood pressure was diagnosed during 511 pregnancies in 458 women. In three out of four cases (383 pregnancies), high blood pressure was associated with a diagnosis of pre-eclampsia, a serious complication of pregnancy. Pre-eclampsia is usually detected by the presence of high levels of protein in the urine and high blood pressure. Pre-eclampsia affects transfer of oxygen across the placenta, affecting foetal growth and raising the risk of stillbirth and premature birth. In severe cases, pre-eclampsia may lead to fits or liver or kidney failure in the mother.

The prevalence of high blood pressure did not change significantly between 2010 and 2020 (3.9% in 2010, 5.8% in 2020).

Both diabetes and high blood pressure were diagnosed during 46 pregnancies in 43 women.

Compared to women who did not develop diabetes or high blood pressure (n=8,231), women who developed one or both conditions during pregnancy were more likely to be aged 35 years or over, to be of Black African or Caribbean descent, to be taking antiretroviral treatment at conception or to be in their first pregnancy.

The prevalence of diabetes during pregnancy rose from 2.7% in 2010 to 10.3% in 2020 (p<0.001). The increase in prevalence accelerated from 2016. As the proportion of women aged 35 or over in the pregnant population increased from 32% in 2010 to 52% in 2020, the researchers say that maternal age may be a driver of the increased prevalence of diabetes. However, the prevalence of diabetes has risen in the UK and Irish populations over the past decade and the study was not able to assess the relationship between another risk factor for gestational diabetes – maternal weight – and the increased prevalence of diabetes.

Looking at the relationship between diabetes, hypertension and adverse pregnancy outcomes, the researchers found that stillbirth was almost five times more common in pregnancies affected by diabetes (1.3% prevalence) and 12 times more common in pregnancies affected by high blood pressure (3.1% prevalence) when compared to pregnancies affected by neither condition (0.26% prevalence).

Although diabetes or high blood pressure were not associated with a higher frequency of emergency caesarean section, there was a trend towards a higher frequency of premature birth in pregnancies affected by high blood pressure.

Women with high blood pressure were much more likely to have a low birth-weight infant (46%) than women with diabetes (13%) or neither condition (7%). One in five infants (21%) born to women with high blood pressure were small for gestational age compared to 6% of infants born to women with diabetes and 8% born to women with neither condition.

Find out more: Adverse pregnancy and birth outcomes in women living with HIV

A published analysis of gestational diabetes by the same research group, using data on pregnancies in women with HIV between January 2010 and June 2020, also reported on antiretroviral exposure. Just under two-thirds of pregnancies (64%) were conceived when women were already taking antiretroviral treatment and the proportion of women on treatment at conception increased from 61% in 2010-2012 to 82% in 2016-2020.

Just over half of pregnancies (51%) were exposed to protease inhibitors but protease inhibitor use declined from 70% in 2010-2012 to 42% in 2016-2020. Sixteen per cent of pregnancies were exposed to an integrase inhibitor.

There was no significant relationship between exposure to any antiretroviral and gestational diabetes. However, women with gestational diabetes were more likely to have started antiretroviral treatment before the third trimester of pregnancy and more likely to have a lower first viral load during pregnancy. The risk of gestational diabetes was significantly lower in women with CD4 counts below 350, possibly reflecting the impact of weight gain accompanying immune restoration on diabetes risk.

In their published analysis, the study investigators say that the increased prevalence of gestational diabetes may be explained by the effects of both HIV and antiretroviral treatment on insulin resistance as well as population-wide increases in obesity. They say that the substantially increased risk of stillbirth in women with the condition requires greater attention to the optimal management of gestational diabetes in women with HIV.