Impact of COVID-19 lockdown on glycemic control in patients with type 1 and type 2 diabetes mellitus: a systematic review

BACKGROUND: In 2019, a new virus known as severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has emerged. Coronavirus disease 2019 (COVID-19) was classified as a pandemic in a short period of time. In order to reduce the spread of COVID-19, many countries have imposed a lockdown with movement restrictions, social distancing and home confinement, which has affected routine healthcare activities and everyday life. The aim of this systematic review was to examine the impact of the COVID-19 lockdown on glycemic control in patients with type 1 diabetes (T1D) and type 2 diabetes (T2D). METHODS: We systematically identified studies by searching the databases Cochrane Library, MEDLINE via PubMed, Web of Science Core Collection, EMBASE, and CINAHL until April 2021. We included n = 33 observational studies of which n = 25 investigated T1D and n = 8 T2D. RESULTS: Overall, we analyzed n = 2881 T1D patients and n = 1823 T2D patients. Glycemic values in patients with T1D improved significantly during lockdown. Overall, n = 18 (72%) T1D studies indicated significant improvements in glycemic outcomes. Meta-analysis revealed a mean difference in HbA1c of − 0.05% (95% CI − 0.31 to 0.21) due to lockdown, and in time in range (TIR) of + 3.75% (95% CI 2.56 to 4.92). Lockdown determined a short-term worsening in glycemic values in patients with T2D. Overall, n = 4 (50%) publications observed deteriorations in glycemic control. Meta-analysis demonstrated a mean difference in HbA1c of + 0.14 (95% CI − 0.13 to 0.40) through the lockdown. Moreover, n = 3 (75%) studies reported a not significant deterioration in body weight. CONCLUSIONS: Glycemic values in people with T1D significantly improved during COVID-19 lockdown, which may be associated with positive changes in self-care and digital diabetes management. In contrast, lockdown rather determined a short-term worsening in glycemic parameters in patients with T2D. Further research is required, particularly into the causes and effective T2D management during lockdown. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13098-021-00705-9.