Hyperglycemia and Insulin Use Increase COVID-19 Complication Risk

Two new studies out of Wuhan, China, the epicenter of COVID infections worldwide, bring more bad news to those living with type 2 diabetes as well as some surprising findings linking non-diabetes related hyperglycemia with poor COVID-19 outcomes.

Both studies come from Yang Jin of the Huazhong University of Science and Technology and draw off data collected in the region between January and February of 2020.

High Blood Sugar Associated with Higher COVID-19 Mortality

The first study, which was published in Diabetologia, looked specifically at fasting blood glucose levels (FBG) of patients without diabetes suffering from COVID-19. High FBG, which was defined as any level at or above 7.0 mmol/L (126 mg/dL), was found in around one-third of all subjects.

Not only did elevated blood sugars increase the risk of complications from COVID-19, but it also greatly increased the mortality risk. 

Of the subjects with elevated FBG, 50.9% suffered in-hospital complications during their first 28 days of hospitalization. This is compared to only 9.2% of patients with normal FBG levels.

Additionally, patients with an FBG of 7.0 mmol/L (126 mg/dL) or higher were 2.3 times more likely to die in the first 28 days of hospitalization than someone with normal blood sugar. Similarly, patients with a moderately elevated FBG (between 6.1 mmol/L and 6.9 mmol/L) (110 to 125 mg/dL) were 1.71 times more likely to die during the same period.

While there have been many studies that have come out in the last few months highlighting the connection between hyperglycemia and increased COVID-19 risk, this is the first to confirm that this risk exists independent of a diabetes diagnosis and only based on blood glucose levels.

What Causes Elevated Blood Glucose in People without Diabetes?

Yang Jin and his colleagues discussed many reasons for why COVID-19 patients who had not been diagnosed with diabetes seemed to be experiencing hyperglycemia at such high rates.

• Previous studies have indicated that one of the side effects of the novel coronavirus infection is acute blood-glucose disorder, which causes elevated blood sugars in normally healthy, diabetes-free patients.
• It is also possible that some patients may develop stress-induced hyperglycemia while critically ill patients may experience acute insulin resistance leading to hyperglycemia.
• Of course, there is always a strong possibility that at least some of the patients seen already had diabetes but had not been diagnosed.

In any case, this study highlights the importance of blood sugar monitoring and control, in all patients who are hospitalized for COVID.

Insulin-Dependent Patients at Higher Risk for Complication

The second study from Yang Jin and his colleagues looked at the associated risk between in-hospital complications and mortality in insulin-dependent people with type 2 diabetes.

• They found, what previous studies have clearly shown, that type 2 patients, in general, are at a greatly increased risk for complications and death from COVID-19.
• They also found that insulin-treated type 2 patients are at the greatest risk within that group.

If someone was being treated with insulin for their diabetes when admitted to the hospital during this study:

• 27.6% were admitted to the ICU compared to only 1.8% of people with diabetes who were not using insulin therapy.
• 51.7% of the insulin-dependent people died while only 3.6% of the non-insulin-dependent population died.

The study noted that insulin-dependent subjects tended to be older and showed lower lymphocyte levels and tended to be more critically ill upon admittance. Insulin-treated patients were also more likely to experience respiratory failure, acute cardiac injury, and kidney injury.

Patients with Diabetes Require More Intensive Care

It has been well-documented that high blood sugar and uncontrolled diabetes increases a person’s risk for stroke, myocardial infarction, community-acquired pneumonia, and other complications often seen in COVID-19 patients.

But we now know that it’s not just patients with diabetes that are likely to suffer from the increased risk for these complications. In fact, as many as 30% of patients who don’t have diabetes may be suffering from elevated blood sugars when admitted to the hospital for COVID symptoms.

Insulin use increases these risks, even more, putting insulin-treated COVID patients at an even higher risk for complications and death than their non-insulin-treated counterparts.

Both of these studies continue to highlight a growing need for intense blood sugar management and monitoring not only in patients known to have diabetes but in anyone admitted to the hospital for COVID-19 symptoms.