Post-COVID-19 syndrome, inflammation and insulin resistance: a retrospective cohort study

BACKGROUND

COVID-19-induced diabetes is a novel and enigmatic disease. Our aim was to evaluate a possible relationship between post-COVID-19 syndrome (PCS) and increased insulin resistance (IR) in non-diabetic outpatients after mild COVID-19.

METHODS

Repeated measures design. Three evaluations [1E (pre-COVID, baseline), 2E (3 months post-COVID) and 3E (21 months post-COVID)] were performed, directed to PCS+ and PCS- subjects. Triglyceride-glucose (TyG) index ≥8.74 was considered IR, and albumin-to-globulin ratio (AGR) <1.50, inflammation.

RESULTS

We analyzed 112 individuals (median [IQR] age=44 [20] years, 58% women, 36 PCS+, 76 PCS-). PCS+ with very low basal IR (TyG <7.78, lowest quartile) showed a reduced inflammatory burden (basal AGR=1.81 [0.4] vs. 1.68 [0.2] in 2E; P=0.23), and increased TyG across evaluations (from basal 7.62 [0.2] to 8.29 [0.5]; P=0.018]. Conversely, PCS+ subjects with high basal TyG (TyG ≥8.65, highest quartile) did not show significant variations in TyG, but a greater inflammatory load (basal AGR=1.69 [0.3] vs. 1.44 [0.3] in 2E; P=0.10). In multivariable models addressing groups with reduced basal IR (TyG <8.01), PCS has been a consistent predictor for TyG, after adjusting for confounders. Partial correlation and multivariable analyses showed similarities involving acute polysymptomatic COVID-19 and PCS regarding IR.

CONCLUSIONS

PCS was associated with increased IR, being more evident when the baseline degree of IR was very low. PCS and increased IR were separately associated with inflammation. Acute polysymptomatic COVID-19 and PCS could be clinical expressions of underlying inflammatory state, which in turn may also trigger IR.