ObjectiveThe objective of our study was to evaluate the impact of the lockdown period on the glycemic balance in patients with GDM.MethodsA retrospective study in one center (Lille, France) compared two periods: the COVID-19 lockdown of 18 March 2020 to 7 May 2020 versus the same period during 2019. Glucose targets were defined by a capillary fasting glucose target < 5.1mmol/L and/or a 2-hour postprandial capillary glucose < 6.6 mmol/L. GDM control was defined as: good (< 20% of the glycemic values were not within the target range), acceptable (20 to 40% of the glycemic values were not within the target range) or poor (> 40% of the glycemic values were not within the target range).ResultsTwo hundred twenty-nine patients were included in 2019 and 222 in 2020. The same mean number of capillary blood sugar tests was performed by the two groups. Postprandial blood sugar was significantly less well controlled in 2020, with a lower rate of good control (61.6% vs 69.4%) and higher rates of acceptable (24.7% vs 21.8%) and poor control (13.7% and 8.7%) (p < 0.05). Use of insulin therapy was significantly higher in 2020 compared with 2019 (47.7% and 36.2%, respectively; p < 0.05).ConclusionDiabetes control was lower during the COVID-19 pandemic lockdown, even if follow-up was not impacted. This may be explained by reduced physical activity, modified dietary habits and anxiety during this period.