According to the largest study to this date, people with Type 1 diabetes had 3,5 times the odds of dying in hospital with Covid-19 compared to those without diabetes. The odds for Type 2 diabetes of dying in hospital with COVID-19 is much smaller. It is 2,03 compared to those without diabetes. The difference is striking. After adjustments for diagnosed cardiovascular comorbidities, the difference remained: there was still an additional risk of 186% for people with Type 1 diabetes and 81% for those with Type 2 diabetes compared to people without diabetes. (1)
Generally increased risk of common infections is observed for Type 1 diabetes that is more pronounced in most types of infection than for Type 2 diabetes. (2)
In diabetes Type 1 heart rate variability (HRV) is impaired after the onset of the disease. (3) Aggregation of cardiovascular risk factors may exacerbate parasympathetic nervous impairment independently of glycemic control problems in Type 1 diabetes. (4)
Impaired heart rate variability may be a prognostic marker of COVID-19 and also a tool for assessing the severity of the disease. Especially the low-frequency domain of HRV is meaningful in estimating the poor outcome of severe infections and sepsis. (5)
Pulmonary functions are also improving in Type 1 diabetes by restoring proinsulin c peptide and insulin production due to simultaneous pancreas and kidney transplantation. (6) Interesting that HRV seems to positively correlate with pulmonary functions that may at least partially explain the pulmonary improvement of the restoration of endogenous insulin and c peptide production of Type 1 diabetes patients. (7)
Proinsulin C-peptide replacement significantly increases HRV in Type 1 diabetes patients. (8) For this reason, proinsulin C-peptide replacement therapy would be an easy way to improve the odds of surviving of Type 1 diabetes mellitus patients and possibly of the general population: centrally/intranasally administered proinsulin c-peptide maybe even a more effective way for stabilizing HRV. (9)(10) The elderly population that is most affected by the severe outcome of COVID-19 often have decreased proinsulin c peptide production capacity along with impaired HRV values. (11)(12)

(1) Barron al.: Type 1 and Type 2 diabetes and COVID-19 related mortality in England: a whole population study, (This version posted 19th May 2020. The copyright holder of this pre-print (which has not been certified by peer review) is NHS England.)

(2) Muller L.M.A.J.: Increased Risk of Common Infections in Patients with Type 1 and Type 2 Diabetes Mellitus, In: Clinical Infectious Diseases 2005; 41:281–8.

(3) Kardelen F. et al.: Heart Rate Variability and Circadian Variations in Type 1 Diabetes Mellitus. In: Pediatr Diabetes. 2006 Feb;7(1):45-50.

(4) Franca de Silva, A.K. et al.: Relationship of the Aggregation of Cardiovascular Risk Factors in the Parasympathetic Modulation of Young People with Type 1 Diabetes, In: Medicina (Kaunas). 2019 Sep; 55(9): 534.

(5) Mageed N.A.: Predictive and Prognostic Value of Heart Rate Variability Analysis in Early Bedside Diagnosis and Management of COVID-19 Patients, In:

(6) Dieterle C.D. et al.: Pulmonary Function in Patients With Type 1 Diabetes Before and After Simultaneous Pancreas and Kidney Transplantation, In: Transplantation. 2007 Mar 15;83(5):566-9.

(7) Behera J.K. et al.: Heart Rate Variability and its Correlation with Pulmonary Function Test of Smokers, In: Heart Views. 2013 Jan-Mar; 14(1): 22–25.

(8) Johansson, B.L. et al.: C-peptide Improves Autonomic Nerve Function in IDDM Patients, In: Diabetologia. 1996 Jun;39(6):687-95.

(9) Okamoto, S. et al.: Proinsulin C Peptide Obviates Sympathetically Mediated Suppression of Splenic Lymphocyte Activity in Rats, In: Diabetologia. 2000 Dec;43(12):1512-7.

(10) Derkach K.V. et al.: Intranasal Administration of Proinsulin C-Peptide Enhances the Stimulating Effect of Insulin on Insulin System Activity in the Hypothalamus of Diabetic Rats, In: Bull Exp Biol Med. 2019 Jul;167(3):351-355.

(11) Chang al.: Aging and Insulin Secretion, In: Am J Physiol Endocrinol Metab . 2003 Jan;284(1):E7-12.

(12) Yadav, K.P.S. et al.: Study of the Aging Effects on HRV Measures in Healthy Subjects, In: International Journal of Computer Theory and Engineering, Vol. 4, No. 3, June 2012.