Corneal endothelial morphology and central thickness in patients with type II diabetes mellitus

To investigate corneal endothelial cell density and morphology in type II diabetic and non-diabetic patients and to relate potential differences to the glycaemic status.

A prospective clinical study including 107 patients with type II diabetes and 128 non-diabetic patients. Sample size was based on a power calculation (power = 0.90; p = 0.05). The diabetic patients had on average more than four HbA1c tests performed (mean 4.1; range 2-14) with intervals of at least 3 months as a reflection of the long-term glycaemic status. The controls had no diabetes confirmed by two causal blood tests. The endothelial cell density, the variation in endothelial cell size (CV), the percentage of hexagonal cells, and the central corneal thickness (CCT) were recorded.

Type II diabetic subjects did not differ from the non-diabetic control subjects with regards to endothelial cell density, hexagonality or variation in CV, but showed a significant increase in CCT (538 versus 546 μm, p < 0.05). In the diabetic group, lower cell counts were associated with higher HbA1c values (p < 0.05). The HbA1c did not, however, have any impact on the CCT.

Type II diabetes has no impact on corneal cell density or morphology in subjects with good glycaemic status. However, higher HbA1c was associated with lower endothelial cell density. CCT was significantly increased in the diabetic group.