Strict stay-at-home orders have been put in place across the world to reduce the spread of the SARS-CoV-2 virus, and there have been concerns that the resulting changes in daily routine, stress, diet, physical activity and access to diabetes services could have a negative effect on glycaemic control in people with diabetes. However, two recent studies suggest limited, or even beneficial, effects in users of flash or continuous glucose monitoring (CGM).
The first study, a retrospective review of 92 people in Spain, compared glucose metrics over two-week periods prior to and during the early stages of the Spanish national lockdown (Mesa et al, 2020). Overall, the mean Time In Range (TIR) increased significantly, by 3.3 percentage points, during lockdown, driven mainly by significant reductions in time spent in hyperglycaemia (time in hypoglycaemia was not reduced, although nearly 40% of participants achieved a Time Below Range of <4%). Mean blood glucose fell from 8.9 to 8.5 mmol/L.
The second study, conducted in Edinburgh, evaluated glucose metrics in 572 users of flash glucose monitoring who had sensor data available for two-week periods prior to and 7 weeks into the UK lockdown (Dover et al, 2020). During lockdown, mean TIR increased significantly by 3 percentage points, with associated improvements in glucose variability and estimated HbA1c. However, there was a small but significant reduction in the number of people who achieved a Time Below Range of <5% (64% of participants before lockdown vs 58% after lockdown).
A number of potential reasons are proposed to explain the improved glycaemic control observed in the two studies. More regular patterns of daily life, more home-cooked food allowing more accurate carbohydrate counting, easier administration of meal-time boluses and decreased workloads may all have helped to improve glucose control.
However, the Edinburgh study outlined some important exceptions to the trend of improved glycaemic control. Overall, 22% of participants had a ≥5% reduction in TIR. Those in the top two quintiles for socioeconomic deprivation were more likely to have an increase in TIR, and deprivation was the only independent predictor of a ≥5 mmol/mol (0.5%) increase in estimated HbA1c, which occurred in 16% of participants. These findings may have been due to worse diet and reduced exercise during lockdown, as well as increased stress from childcare commitments and precarious employment and income.
Dover AR, Ritchie SA, McKnight JA et al (2020) Assessment of the effect of the COVID-19 lockdown on glycaemic control in people with type 1 diabetes using flash glucose monitoring. Diabet Med 2 Aug [epub ahead of print]. https://doi.org/10.1111/dme.14374
Mesa A, Viñals C, Pueyo I et al (2020) The impact of strict COVID-19 lockdown in Spain on glycemic profiles in patients with type 1 diabetes prone to hypoglycemia using standalone continuous glucose monitoring. Diabetes Res Clin Pract 167: 108354. https://doi.org/10.1016/j.diabres.2020.108354