Marijn S. Hendriksz¹, Ricky Siebeler², Julia I.P. van Heck¹, Clementine E.M. Verhulst¹, Marten A. Hoeksema², Menno P.J. de Winther², Bastiaan E. de Galan^1,3, Cees J. Tack¹, Rinke Stienstra^1,4

Marijn.Hendriksz@radboudumc.nl

1.Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands. 2. Department of Medical Biochemistry, Experimental Vascular Biology, Amsterdam UMC, University of Amsterdam, the Netherlands. 3. Department of Internal Medicine, Maastricht University Medical Centre, MUMC+, Maastricht, The Netherlands. 4. Division of Human Nutrition and Health, Wageningen University, Wageningen, the Netherlands.

Background: A single experimental hypoglycaemic event in people with type 1 diabetes and in healthy controls increases absolute numbers of circulating monocytes, an effect that is sustained up to 7 days. However, the acute and prolonged impact of hypoglycaemia on monocyte function remains largely unknown. Therefore, we used RNA sequencing to study gene expression changes in circulating monocytes during hypoglycaemia and after 7 days in people with type 1 diabetes and healthy controls.

Methods: Adults with type 1 diabetes (n=25) and matched controls (n=8) underwent a hyperinsulinaemic-euglycaemic hypoglycaemic (2.8 ± 0.1 mmoL/L [49.9 ± 2.3 mg/dL]) glucose clamp for 60 minutes. During euglycaemia, hypoglycaemia and 7 days later, blood was drawn, RNA was isolated from monocytes and used for RNA sequencing.

Results: In the healthy control group, data analyses revealed 219 and 117 differentially expressed genes (FDR < 0.05, Log2FoldChange > 0.5) during hypoglycaemia and 7 days later, respectively, when compared to euglycaemia. In the type 1 diabetes group, 91 differentially expressed genes were found during hypoglycaemia and 226 after 7 days. Pathways that were most significantly enriched (FDR < 0.05) in the healthy control group during hypoglycaemia included regulation of cell adhesion and several inflammatory pathways. After 7 days, the highest enriched pathways were mainly associated with mitochondrial metabolism, transcription and translation. In the diabetes group, most significantly enriched pathways (FDR < 0.05) during hypoglycaemia were related to protein tyrosine kinase signaling, and transcription and methylation after 7 days.

Discussion/conclusion: A single experimental hypoglycaemic event induces acute and prolonged transcriptional changes in circulating monocytes of both people with type 1 diabetes and healthy controls. However, groups differed with respect to significantly enriched pathways. Further research is needed to identify the signals that drive monocyte transcriptional changes and to determine the downstream consequences for monocyte function.