Quote from the notice for diabetics about COVID:

Diabetes causes inflammation in the body and you have a harder time fighting off an infection like the virus that causes COVID-19

What does it mean "diabetes causes inflammation"? I know there are a lot of short-term problems like hyperglycemia, hypoglycemia and long-term complications diabetes may cause, like neuropathy, retinopathy, and a lot more over time, but it's first time I hear about inflammation caused by diabetes. Like what it is exactly, does it mean that all diabetics have some kind of constant inflammation in their body and that is aggravated when they get sick? Or they refer to one of those complications/problems as inflammation (which I think is not correct).

  • There's a recent paper here which seems to cover the topic, though my biochemistry isn't good enough to parse it into a good answer without many hours study. Jun 4, 2022 at 15:41
  • The possibility more pertinent question is why does inflammation lead to diabetes? Because markers for chronic inflammation are present long before T2D is diagnosed. Jun 5, 2022 at 13:11

1 Answer 1


As @anongoodnurse pointed out, a pre-inflammatory state is present before T2D develops. Most of the patients of Type 2 Diabetes mellitus are obese. They may have dyslipidemia wherein sub-acute chronic inflammation is common.

The most common and well studied pathway is Inflammasome/IL-1β signalling. Cells have cytosolic NOD-like receptors that recognize diverse molecules that are liberated or altered. They signal via a multiprotein complex called the Inflammasome. Excess free fatty acids within macrophages and β-cells can lead to Inflammasome activation which activates an enzyme (caspase-1) which cleaves precursor form of IL-1β to it's active form. IL-1β mediates the secretion of other pro-inflammatory cytokines from macrophages, islet cells and other cells.

This is just one mechanism through which inflammation can occur. Others include accumulation of DAG, phospholipids, ceramides, etc. which are toxic lipid metabolites that can attenuate signalling through the insulin receptor and activate inflammatory pathway in the islets. Liver steatosis can also lead to inflammation and hepatocyte injury which can impair glucose homeostasis.


  1. Robbins and Cotran Pathologic Basis of Disease, 10e

  2. Tsalamandris, S., Antonopoulos, A. S., Oikonomou, E., Papamikroulis, G. A., Vogiatzi, G., Papaioannou, S., Deftereos, S., & Tousoulis, D. (2019). The Role of Inflammation in Diabetes: Current Concepts and Future Perspectives. European cardiology, 14(1), 50–59. https://doi.org/10.15420/ecr.2018.33.1

  3. Remmerie, A., & Scott, C. L. (2018). Macrophages and lipid metabolism. Cellular immunology, 330, 27–42. https://doi.org/10.1016/j.cellimm.2018.01.020

  • Thanks for the input. However it's still not clear how T1D affects the inflamation then? And why COVID can cause more severe consequences for T1D patients compared to people without diabetes. Jun 20, 2022 at 13:44
  • T1D is an autoimmune disease in which self reactive T-cells attack B-cells which can lead to their injury due to which inflammation occurs. As T1D comprises only about 10% of the case of diabetes, I didn't write it in the answer. In case of covid, the most feared complication is cytokine storm which is an uncontrolled generalized immune response. If an autoimmune disease or inflammation is already present in the body, I think it may lead to or aggravate this complication.
    – Mesentery
    Jun 20, 2022 at 14:46
  • Moreover, hyperglycemia can cause oxidative stress which can lead to inflammation. It is also thought to cause dysfunction of the immune system. Lastly, Insulin also has some anti-inflammatory and anti-apoptopic effects. As you can see there is no single answer to the question, it is multifactorial.
    – Mesentery
    Jun 20, 2022 at 14:59

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