Ibrahim Mohammed and Georgios Ponirakis
Background/Aim: Continuous glucose monitoring (CGM) has revealed that glycemic variability (GV) and low time in range (TIR) are associated with albuminuria and retinopathy. We have investigated the relationship between CGM metrics and highly sensitive markers of nerve pathology using corneal confocal microscopy (CCM) in participants with type 1 and type-2 diabetes.
Methods: A total of 40 participants with diabetes and 28 healthy controls underwent quantification of corneal nerve fiber density (CNFD), corneal nerve branch density (CNBD), corneal nerve fiber length (CNFL) and inferior whorl length (IWL). Participants with diabetes underwent CGM for 4 consecutive days.
Results: CNBD was significantly lower in patients with high GV compared to low GV median (range) (25.0(19.0-37.5) vs. 38.6(29.2-46.9); P=0.007); in patients who spent >4% compared to <4% time below range (54-69 mg/dl) (25.0(22.9-37.5) vs. 37.5(29.2-46.9); P=0.045) and in patients who spent >1% compared to <1% time in severe hypoglycemia (<54 mg/dl) (25.0 (19.8-41.7) vs. 35.4 (28.1-44.8); P=0.04). Duration in hyperglycemia and severe hyperglycemia did not correlate with CNFD (P>0.05), CNBD (P>0.05), CNFL (P>0.05) or IWL (P>0.05), but duration in hypoglycemia correlated with CNBD (r=-0.342, P=0.031).
Conclusions: Greater glucose variability and duration in hypoglycemia, rather than hyperglycemia are associated with nerve fiber loss in diabetes.
