Medical Nutrition Therapy for Gestational Diabetes Mellitus (GDM) Based on Mediterranean Diet Principles

Background: Medical nutrition therapy (MNT) is the first-line therapy to achieve glycemic control in women with gestational diabetes mellitus (GDMw). It has been associated with better pregnancy outcomes. Whether MNT can make pregnancy outcomes like women without GDM remains unknown.

Objective: To assess if a Mediterranean-diet-based medical nutrition therapy (MNT) facilitates near-normoglycemia (determined by HbA1c levels) at 36-38 gestational weeks in GDMw, and observe its effects on adverse pregnancy outcomes.

Study Design: A sub-analysis of the St Carlos GDM Prevention Study. It was conducted between January-December 2015 in the Hospital Clínico San Carlos (Madrid, Spain). One thousand consecutive normoglycemic women were included before 12th gestational weeks, and 874 included in the final analysis: 177 were diagnosed with GDM (IADPSG criteria) and 697 had normal glucose tolerance. GDMw received Mediterranean diet-based MNT, with a daily intake of ≥40 ml extra-virgin olive oil and a handful of nuts (mainly pistachios).

Results: GDMw had higher HbA1c levels, fastinG insulin and HOMA-IR at 24-28 gestational weeks as compared with NGT. At 36-38 gestational weeks these values became similar. Insulin therapy was necessary in 26.6% of GDMw. Rates of macrosomia, large-for-gestational-age, pregnancy-induced hypertensive disorders, prematurity and c-sections were similar between groups. Crude RR analysis showed that GDMw had a higher risk of insufficient weight gain [2.37(1.64-3.30), P=.001], urinary tract infection [1.69(1.20-2.38), P=.005], small-for-gestational age newborns [2.05(1.29-3.24), P=.009] and neonate ICU admission [3.42(1.45-8.04), P=.006].

Conclusions: Using a Mediterranean-diet-based MNT in GDMw helps to achieve a near-normoglycemia, making most pregnancy outcomes similar to women with NGT. The higher rates of small-for-gestational-age and insufficient weight gain require further analysis.