Even mild COVID-19 infection raises blood sugar and risk of incident diabetes

New-onset hyperglycaemia or high blood sugar and insulin resistance have been reported in patients with coronavirus disease-2019 (Covid-19) without a history of diabetes. However, it is unclear whether such metabolic alterations are transient or whether individuals with Covid-19 have an increased future risk of persisting diabetes. Therefore, Dr Wolfgang Rathmann and his team conducted a study to investigate diabetes incidence after infection with Covid-19. Individuals with AURI, which are frequently caused by viruses, were selected as a non-exposed control group.

In a retrospective cohort analysis of the Disease Analyzer, the researchers assessed a representative panel of 1171 primary care physicians' practices throughout Germany between March 2020 and January 2021, with follow-up through July 2021. They evaluated health records of 35,865 adults with COVID-19 without baseline diabetes, propensity score-matched (1:1) by demographic and clinical characteristics with individuals who had AURI. They determined newly diagnosed diabetes based on ICD-10 codes (type 2 diabetes: E11; other forms of diabetes: E12–E14) during follow-up until July 2021 (median for Covid-19, 119 days; median for AURI 161 days). They used regression models to calculate incidence rate ratios (IRRs) for type 2 diabetes and other forms of diabetes.

Key findings of the study:

• During an average follow-up of 119 days for COVID-19 and 161 days for AURI, the researchers observed that the numbers of hospitalisations were similar in both groups.
• They noted that after propensity score matching, demographic and clinical characteristics were similar in 35,865 AURI controls.
• They found that individuals with Covid-19 had an increased type 2 diabetes incidence compared with AURI (15.8 vs 12.3 per 1000 person-years) with an incidence rate ratio (IRR) of 1.28.
• This shows that the relative risk of developing type 2 diabetes in the COVID group was 28% higher than in the AURI group.
• They noted that the IRR was not increased for other forms of diabetes.

The authors concluded, "The present primary care study indicates a temporal relationship between mostly mild Covid-19 and newly diagnosed type 2 diabetes. If confirmed, this study supports the potential relevance of active monitoring of glucose dysregulation after recovery from mild forms of SARS-CoV-2 infection."