In recommending blood sugar testing and control for all COVID-19 patients, a recent study was yet another to recommend that essentially every hospitalized COVID-19 patient should be treated as if they had diabetes:
Glycaemic testing and control are important to all COVID-19 patients even where they have no pre-existing diabetes, as most COVID-19 patients are prone to glucose metabolic disorders.
Researchers from Wuhan found that COVID-19 patients not previously diagnosed with diabetes that are admitted to the hospital with high fasting blood glucose levels are at a much higher risk of death and severe illness.
The study is only the latest of several that have shown that COVID-19 can cause hyperglycemia in people not known to have diabetes, and that such hyperglycemia is extremely dangerous. As a result, many different researchers have independently recommended that clinicians engage in the intensive blood sugar monitoring and manipulation that is characteristic of diabetes even in the many patients that have never been diagnosed with diabetes.
The new study was published online in the journal Diabetologia on July 10. A team of Chinese researchers based in Wuhan itself, the original epicenter of coronavirus infection, took a retrospective look at patients that were admitted to two hospitals in late January and early February. The patients considered in the study were not known to have diabetes when they were admitted, and yet a very high percentage had high fasting blood glucoses upon admittance. Of 605 included in the study, 176 (29%) registered a fasting blood glucose of ? 7.0 mmol/l (? 126 mg/dL), which under normal circumstances is sufficient for a diagnosis of Type 2 diabetes. While some percentage of these patients may have had undiagnosed diabetes, many or most would have been experiencing transient “hyperglycaemia caused by an acute blood-glucose disorder,” a known result of stress and illness observed in many COVID-19 patients.
The group of patients with elevated fasting blood glucose upon admission had markedly worse outcomes: they were roughly three times as likely to die, and twice as likely to experience in-hospital complications, the most common of which were acute liver injury and acute respiratory distress syndrome.
It was in May when we first became aware of new guidelines that doctors should be ready to provide all COVID-19 patients with intensive blood sugar management. An American study (PDF) that analyzed the prevalence of “uncontrolled hyperglycemia” among hospitalized COVID-19 patients concluded that clinicians “should treat hyperglycemia to achieve BG targets < 180 mg/dl for most patients. This equates to basal-bolus insulin therapy in most non-ICU patients and continuous insulin infusion in the critically ill.” Around the same time, the prestigious medical journal The Lancet noted that the phenomenon of “new onset diabetes,” apparently triggered by COVID-19. We were among the first media sources to wonder: Is COVID-19 Causing Diabetes? Since then, evidence has mounted that yes, the novel coronavirus might actually trigger diabetes!
A novel theory by Professor Yaakov Nahmias of Israel’s Hebrew University may explain the mechanism at work: while hyperglycemia in a non-diabetic patient “looks like insulin resistance, it is actually mitochondrial dysfunction. Virus proteins seem to bind specific genetic elements that shut down the mitochondria. Without it, lung cells can’t burn glucose into energy.” The novel coronavirus appears to disrupt cell metabolism, especially in the lungs, in a way that results in rising blood sugars. Professor Nahmias believes that affected lung cells do convert excess glucose into fats that help the virus propagate, which would help account for the fact that patients with higher blood sugars experience significantly worse outcomes.
While many experts are now recommending that the blood sugar levels of COVID-19 patients be managed aggressively, we don’t yet have definitive evidence that such interventions are effective. The rate of death has appeared to slow in the United States and elsewhere, and perhaps our increasing understanding of the importance of glycemic control has played a role in improved outcomes for patients.