Aim:
Type 2 diabetes mellitus (T2DM) is a widespread disease that leads to many complications if not adequately controlled. The pandemic and its limitations on healthcare access impaired the management of chronic conditions. The aim of our study was to examine its effects in context of different antidiabetic therapies on key health related factors in patients with T2DM.

Material and methods:
To the study we enrolled 598 adult patients with diagnosed T2DM treated in diabetology outpatient department of the University Clinical Centre (UCC) of the Medical University of Warsaw. Data on body weight, glycated hemoglobin (HbA1c), and creatinine concentration were collected throughout the first COVID-19 pandemic wave and compared to the results obtained before the 4th of March, 2020 (1st confirmed case in Poland).

Results:
The HbA1c mean baseline level was 7.15% (±1.39) and increased significantly (7,34%, p=0.02) during observation. Importantly, the attendance of patients for HbA1c testing decreased by 57.82% in comparison to the pre-pandemic period. Similarly, creatinine concentrations increased (from 1.27mg/dl (±0.76) 1,34 mg/dl (p=0.004)). The increase in creatinine concentration was significantly lower in the group treated with regimens including metformin compared to other regimens. Somewhat surprisingly, the mean body mass remained unchanged.

Conclusions:
The pandemic period had a significant impact on the tested biochemical parameters. The lesser changes of renal parameters in the group of patients treated with metformin confirms its nephroprotective effect and its value as a first-line treatment in T2DM.