Covid-19 infection increases risk of Type 2 diabetes: Study

People who have had Covid-19 are at increased risk of developing Type 2 diabetes, according to a study.

The study, published in the journal Diabetologia, showed that patients with Covid-19 developed Type 2 diabetes more frequently than people with acute upper respiratory tract infections (AURI), which are also frequently caused by viruses.

The relative risk of developing Type 2 diabetes was 28 per cent higher in the Covid-19 group than in the AURI group, according to a team of researchers from the German Diabetes Center (DDZ), German Center for Diabetes Research (DZD) and IQVIA (Frankfurt).

Previous studies have shown that the human pancreas can also be a target of SARS-CoV-2, the virus causing Covid. Following an infection, reduced numbers of insulin secretory granules in beta cells and impaired glucose-stimulated insulin secretion have been observed.

In addition, after Covid-19 disease, some patients developed insulin resistance and had elevated blood glucose levels although they had no previous history of diabetes. SARS-CoV-2 infection may lead to a strong release of pro-inflammatory signalling substances (cytokines). Activation of the immune system may persist for months after a SARS-CoV-2 infection and impair insulin effectiveness (muscle, fat cells, liver).

To date, however, it is unclear whether these metabolic changes are transient or whether Covid-19 disease increases the risk of persisting diabetes.

To investigate, the team conducted a retrospective cohort study and included 8.8 million patients across Germany from March 2020 to January 2021. Follow-up continued until July 2021.

As a control group, the researchers selected people with AURI. The two cohorts were matched for sex, age, health insurance, month of Covid-19 or AURI diagnosis, and comorbidities (obesity, hypertension, high cholesterol, heart attack, stroke). Patients on corticosteroid therapy were excluded from the study.

During the study period, 35,865 people were diagnosed with Covid-19.

"Our analyses showed that patients with Covid-19 developed Type 2 diabetes more frequently than people with AURI. The incidence of diabetes with Covid-19 infection was 15.8 compared to 12.3 per 1000 people per year with AURI," said first author Wolfgang Rathmann, head of the Epidemiology Research Group at the DDZ.

"Statistical analysis resulted in an incidence rate ratio of 1.28. Put simply, this means that the relative risk of developing Type 2 diabetes was 28 per cent higher in the Covid-19 group than in the AURI group," Rathmann said.

Although Type 2 diabetes is unlikely to be a problem for the vast majority of people with mild Covid-19 disease, the authors recommend that anyone who has recovered from Covid be alert to the warning signs and symptoms, such as fatigue, frequent urination and increased thirst and seek immediate treatment.