Tighter Versus Less-Tight Glycemic Treatment Compares Similarly for Gestational Diabetes Mellitus

Phyllis Ohene-Agyei, PhD candidate

Credit: University of Auckland

A new study did not find adopting a tighter glycemic treatment for women with gestational diabetes mellitus affects their mental health status at 36 weeks of gestation and 6 months postpartum.¹

Gestational diabetes mellitus, a hyperglycemia detected during pregnancy, is the most common metabolic disease experienced in pregnancy. About 1 in 6 pregnant women have this condition, and the prevalence is rising worldwide. Gestational diabetes mellitus can affect pregnancies by increasing high blood pressure, as well as increasing the risk of having a large baby and needing a c-section.² A baby is also at a higher risk of being born prematurely, having low blood sugar, and developing type 2 diabetes.

New Zealand experienced an annual 14% increase in prevalence from 2001 – 2014, and the United States had an increase from 0.3% in 1979 – 1881 to 5.8% in 2008 – 2010.1 Gestational diabetes mellitus is associated with perinatal mental disorders, such as depression. In fact, 2 studies demonstrated women with a diagnosis of gestational diabetes mellitus were 2 – 4 times more likely to experience perinatal depression than women without gestational diabetes mellitus.

Because of gestational diabetes mellitus’ association with perinatal mental disorders, a new secondary analysis, led by Phyllis Ohene-Agyei, a PhD candidate, from the Liggins Institute at University of Auckland in Auckland, New Zealand, compared 2 different glycemic treatment targets for women with gestational diabetes mellitus, such as tight versus less-tight glycemic treatment targets, to combat mental health issues.

Recommended glucose levels vary. For instance, the American Diabetes Association recommends fasting plasma glucose of < 95 mg/dL (< 5.3 mmol/L); 1-h postprandial < 140 mg/dL (< 7.8 mmol/L); and 2-h postprandial < 120 mg/dL (< 6.7 mmol/L) [39], and the World Health Organization recommends fasting plasma glucose of ≤ 7.0 mmol/L (≤ 126 mg/dl); and 2-h postprandial ≤ 9.0 mmol/L (≤ 160 mg/dl) [41].

“Most of these recommendations are not based on evidence from clinical trials but rather guideline panel consensus, with the relevant Cochrane systematic review reporting insufficient evidence on optimal glycemic targets to minimise adverse maternal and fetal health outcomes,” the investigators wrote.

The study used data from women who had already consented to complete perinatal mental health questionnaires for the TARGET Trial, a randomized trial in 10 hospitals in New Zealand. At first, the investigators used less-tight glycemic targets to manage gestational diabetes, following New Zealand’s glucose level guidelines (fasting plasma glucose < 5.5 mmol/L (< 99 mg/dl); 1-h postprandial < 8.0 mmol/L (< 144 mg/dl); 2-h postprandial < 7.0 mmol/L (< 126 mg/dl). Then, participants were randomized into 2 clusters for 4-monthly intervals, and the investigators switched over to using tighter glycemic targets ((fasting plasma glucose ≤ 5.0 mmol/L (≤ 90 mg/dl), 1-h postprandial ≤ 7.4 mmol/L (≤ 133 mg/dl); 2-h postprandial ≤ 6.7 mmol/L (≤ 121 mg/dl).

The team collected data from the 414 participants on anxiety (6-item Spielberger State Anxiety scale), depression (Edinburg Postnatal Depression Scale), and health-related quality of life (36-Item-Short-Form General Health Survey) at baseline (or time of diagnosis), 36 weeks of gestation, and 6 months of postpartum).

The Edinburg Postnatal Depression Scale, used to assess postpartum depression among pregnant women, had a cut-off score of > 12, indicating significant vulnerability to depression. The investigators measured anxiety with a shortened 6-item Spielberger State-Trait Anxiety Inventory because it still holds validity. Then, the 36-item Short-Form General Health Survey assesses 9 aspects of health status: general health, mental health, physical functioning, social functioning, role physical, role emotional, bodily pain, and vitality.

Women were recruited to the TARGET trial between May 29, 2015 – November 7, 2017, with 225 (54.3%) women randomized to tighter glycemic targets and 189 (45.7%) to the less tight targets. More European women were in the less-tight treatment group, and more Pacific women were in the tighter treatment group. Moreover, most of the women in the study were overweight or obese (90%), and the tighter target group had more obese women.

The primary outcome was the composite poor mental health—a combination of anxiety, vulnerability to depression, or poor mental health-related quality of life. Overall, Ohene-Agyei and colleagues found no difference between the 2 glycemic target groups at week 36 (relative risk [RR], 1.07; 95% CI, 0.58 – 1.95) and 6 months postpartum (RR, 1.03; 95% CI, 0.58 – 1.81).

For mental health outcomes, there were no differences for patients in the tight glycemic treatment group versus the less-tight treatment group. At 36 weeks, the relative risk for mental health outcomes was the following: anxiety: RR: 0.85; 95% CI, 0.44 – 1.62), vulnerability to depression (RR, 1.10; 95% CI, 0.43 – 2.83), or poor mental health-related quality of life (RR, 1.05; 95% CI, 0.50 – 2.20). Then, for 6 months postpartum, the relative risks were: anxiety (RR: 1.21; 95% CI, 0.59 – 2.48), vulnerability to depression (RR, 1.41; 95% CI, 0.53 – 3.79), and poor mental health-related quality of life (RR, 1.11; 95% CI, 0.59 – 2.08).

“We found no difference in maternal mental health outcomes, namely anxiety, depression, and health-related quality of life, measured at 36 weeks’ gestation and 6 months after birth among women with [gestational diabetes mellitus] treated with tighter recommended glycaemic treatment targets compared to the previously used less tight glycemic targets in New Zealand,” the investigators wrote. “These findings suggest adoption of tighter glycaemic treatment targets in [gestational diabetes mellitus] care does not appear to benefit nor harm maternal mental well-being assessed at 36 weeks and 6 months after the birth.”

References

1. ^{Ohene-Agyei, P., Tran, T., Harding, J.E. et al. Do glycaemic treatment targets affect the perinatal mental health status of women with gestational diabetes? – Data from the TARGET Trial. BMC Pregnancy Childbirth 23, 869 (2023). https://doi.org/10.1186/s12884-023-06190-4}
2. ^{Gestational Diabetes. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/gestational.html#:~:text=Every%20year%2C%202%25%20to%2010,are%20affected%20by%20gestational%20diabetes. Accessed December 19, 2023.}