Reduced HbA1c testing, and remote consultations may result in many people not being diagnosed with type 2 diabetes, whilst there may also be a direct effect of the virus leading to many cases of a secondary diabetes more like type 1 says a leading doctor on COVID and diabetes, speaking at the Diabetes Professional Conference 2021.

The interactions between COVID and diabetes were discussed in a session at this year’s in-person conference by Dr David Strain, Diabetes and Vascular Research Centre, University of Exeter Medical School, and clinical lead for COVID at the Royal Devon & Exeter NHS Foundation Trust.

Interactions between COVID and diabetes are three-fold, he stated:        • there is the impact of COVID on patients with diabetes;                                  • the impact of diabetes on COVID outcomes;                                                   • and the impact of the COVID response on diabetes, explained Strain, who is also chair of the DPC 2021 conference. “

People living with diabetes have poorer outcomes with COVID. It was unclear whether those with diabetes got more COVID, indeed, there was a suggestion that they may have got less COVID, however if they do catch it, it is clear that they have worse outcomes,” said Strain.

He pointed out that the decline of immunity post-vaccine is quicker in people with diabetes. “People with poorly-controlled diabetes are around 40% more likely to experience vaccine failure, and even with well-controlled diabetes you are around 20% more likely to get vaccine failure and have a break-through infection. This is why we’re strongly encouraging people with diabetes to come forward,” said Strain.

As over-50s and vulnerable people are currently being called for a booster COVID vaccine, he also emphasised that, “Now, we know that people with diabetes are more likely to experience vaccine failure and have poorer outcomes after their first vaccination course,” said Strain. He emphasised the importance of receiving the booster and that, “we expect the booster vaccine to have a much longer lasting benefit, around 12-15 months possibly, and this is unlikely to be a booster needed every six months, as some are starting to worry about.”

Commenting on Strain’s talk was Dr Marc Evans, consultant physician in diabetes and endocrinology at University Hospital Llandough in Cardiff, Wales. “There’s a particular concern with the longer-term implications of the pandemic with respect to impact on people with diabetes from the perspective of longer term metabolic and risk factor control,” he said.

“Along with increasingly recognised association of COVID-19 and incident diabetes, this raises many questions for future care planning, as we may be facing a burden of unrecognised diabetes in the community along with many people presenting with deteriorating metabolic and risk factor control, both consequent upon the challenge of care delivery and biological impact of SARs-CoV2.”

High sugar levels in diabetes associated with worse COVID outcomes

In an interview with Medscape News UK, Strain explained that the reason for this is that levels of the ACE-2 enzyme, that COVID uses to enter the body and is designed to protect us from vascular disease, is reduced in diabetes. “Long-term raised blood sugar reduces levels of this enzyme. This is also why people with long-term diabetes have poorer outcomes after stroke and heart attacks.”

However, Strain pointed out that theoretically people with diabetes have less risk of catching COVID because they might distance more among other reasons, but once they do, they experience poorer outcomes, and higher mortality. “This is very much related to higher blood sugars.”

COVID can lead to diabetes characterised by low insulin – many cases undiagnosed

Speaking to the known finding that COVID can precipitate insulin deficiency, Strain explained that the SARS-CoV2 virus uses the ACE-2 enzyme to enter cells, including the beta cells of the pancreas. “In a test tube, we see this triggers the same cell death as seen in type 1 diabetes, so early on in the pandemic we saw that high blood sugar was a common feature of patients presenting with COVID, even in those without pre-existing diabetes.”

“It looked like these people had a new diagnosis of type 1 diabetes. For most people this seemed to improve over time but some were left needing long-term treatment,” he added.

Strain noted that these patients might have presented later on anyway, and perhaps it was just infection pushing them over the edge. “But we are starting to see that numbers are higher than expected.”

Data from the first cohort in China – a population with a very low incidence of diabetes -  found that upon six-month follow up, 2.35% had diabetes. In England a cohort of 50,000 hospitalised COVID patients show that just under 4.9% were diagnosed with diabetes at five months. “That in itself is much higher than expected and can’t be accounted for by the short course of steroids which can create insulin resistance.”

Figures in the community might also reflect an increase in diabetes diagnosis. “These are figures in hospitalised patients. We don’t know about rates in those who had COVID in the community but they could be just as high,” Strain pointed out, adding that part of this might be related to the lack of in-person consultations.

“Because we’ve had more virtual consultations where most often, HbA1c cannot be done to test for diabetes, the number of cases are unknown right now. There is a place for face-to-face visits where the GP has a sixth sense about doing a diabetes test in someone without diabetes.”

During the first nine months of the pandemic, compared to national rates of new diagnoses, there were 60,000 fewer cases of diabetes diagnosed, and 63,000 fewer HbA1c tests. “These numbers are probably much higher now that we are 18 months in,” said Strain.

There is a mechanistic association where COVID increases insulin resistance by affecting the capillaries in insulin delivery and reducing insulin production in the pancreas through damage to beta cells, he explained.

“And these are in patients who have been hospitalised,” he added. “We know acute hyperglycaemia is important prognostically. Acute hyperglycaemia upon hospital admission is a good indicator that the patient is very sick.

Post-COVID patients are showing more rapidly progressing vascular disease too, and Strain noted that they were seeing more people with heart failure. “We thought it was lack of appointments with their doctors, but it appears that it is COVID that’s leading to chronic disease progressing quicker.”

CPI: Professor Strain has declared no relevant conflicts of interest. 

Presented at the Diabetes Professional Conference 2021, November 10, 2021.



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