March 04, 2019
2 min read

Metformin appears safe in treating hyperglycemia during pregnancy

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Among indigenous and nonindigenous women in Australia, the use of metformin in treating hyperglycemic conditions during pregnancy, such as type 2 diabetes, gestational diabetes and newly diagnosed diabetes, does not lead to serious adverse events, according to findings published in the Journal of Diabetes.

“Although the use of metformin in pregnancy is not currently endorsed by many international clinical guidelines, its use has increased recently following key publications,” Louise J. Maple-Brown, PhD, professor and senior principal research fellow at Menzies School of Health Research in the Northern Territory of Australia, and colleagues wrote. “Both relatively high rates of metformin use and higher rates of adverse perinatal outcomes among indigenous women may contribute to greater power to address this knowledge gap.”

Maple-Brown and colleagues included 1,649 pregnancies from the Northern Territory Diabetes in Pregnancy Clinical Register for analysis. All mothers had some type of hyperglycemia, including type 2 diabetes, gestational diabetes or newly diagnosed diabetes in pregnancy. Mothers with type 1 diabetes were excluded.

Women who consented were first referred to the register by a health care provider, and data were entered in the register at time of referral and at delivery. Baseline information collected included age, ethnicity, location, diabetes type, BMI, hypertension status, smoking and alcohol status, and oral glucose tolerance test results. At delivery, additional information pertaining to diabetes medication during the third trimester, location of delivery, gestational age, birth weight and any complications were further recorded.

The most common hyperglycemic condition among the cohort was gestational diabetes (73.2%), followed by type 2 diabetes (16.5%) and newly diagnosed diabetes in pregnancy (10.3%). Compared with nonindigenous women, indigenous women had higher rates of type 2 diabetes (28.8% vs. 4.5%) and newly diagnosed diabetes in pregnancy (13.5% vs. 7.1%). The researchers noted that 90% of indigenous women used metformin for type 2 diabetes treatment in 2016 and that 100% of nonindigenous women did so as well. Metformin use among nonindigenous women with type 2 diabetes increased from 43% in 2012 to the 100% mark in 2016.

“Rates of metformin use in our clinical register are high, particularly among indigenous women, whereas for nonindigenous women, metformin use increased over the 5 years,” the researchers wrote. “This clinical practice reflects the use of both local guidelines and contextual challenges of remote indigenous health, including poverty, food insecurity, high health staff turnover and limited specialist support.”


Shorter gestational age was associated with metformin use in indigenous (P < .001) and nonindigenous (P = .022) women with gestational diabetes or newly diagnosed diabetes in pregnancy after adjusting for age, BMI and insulin use. Births before 37 weeks of gestation were also associated with metformin use in women with either condition, but not to a statistically significant degree. Furthermore, when excluding women who underwent medical nutrition therapy by itself, the association was lost.

The researchers also found that when comparing metformin use with non-use among both groups of women, there was not a statistically significant difference in cesarean section (adjusted OR = 1.25; 95% CI, 0.87-1.81), large for gestational age (aOR = 1.5; 95% CI, 0.9-2.5) or serious neonatal adverse events (aOR = 1.32; 95% CI, 0.68-2.57).

“The epidemic of [type 2 diabetes] in indigenous peoples is clearly evident from the clinical register, with one-third of indigenous mothers with hyperglycemia in pregnancy having pre-existing [type 2 diabetes], and nearly half the indigenous mothers having either pre-existing or likely newly diagnosed [type 2 diabetes],” the researchers wrote. “Optimizing glycemia in women with pre-existing diabetes in pregnancy contributes to improved outcomes; thus, it is a clinical priority to improve care for these women and potentially influence the metabolic health of mother and child lifelong.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures.