Association between diabetic foot ulcer and diabetic retinopathy

Abstract

Purpose: We aimed to investigate the prevalence of diabetic retinopathy (DR) in patients with diabetic foot ulcer (DFU) and elucidate the association between DR and DFU severities and their shared risk factors.

Methods: A retrospective review was conducted on DFU patients who underwent ophthalmic and vascular examinations within 6 months; 100 type 2 diabetic patients with DFU were included. The medical records of 2496 type 2 diabetic patients without DFU served as control data. DR prevalence and severity were assessed in DFU patients. DFU patients were compared with the control group regarding each clinical variable. Additionally, DFU patients were divided into two groups according to DR severity and compared.

Results: Out of 100 DFU patients, 90 patients (90%) had DR and 55 (55%) had proliferative DR (PDR). There was no significant association between DR and DFU severities (R = 0.034, p = 0.734). A multivariable analysis comparing type 2 diabetic patients with and without DFUs showed that the presence of DR [OR, 226.12; 95% confidence interval (CI), 58.07-880.49; p < 0.001] and proliferative DR [OR, 306.27; 95% CI, 64.35-1457.80; p < 0.001), higher HbA1c (%, OR, 1.97, 95% CI, 1.46-2.67; p < 0.001), higher serum creatinine (mg/dL, OR, 1.62, 95% CI, 1.06-2.50; p = 0.027), older age (years, OR, 1.12; 95% CI, 1.06-1.17; p < 0.001), higher pulse pressure (mmHg, OR, 1.03; 95% CI, 1.00-1.06; p = 0.025), lower cholesterol (mg/dL, OR, 0.94; 95% CI, 0.92-0.97; p < 0.001), lower BMI (kg/m2, OR, 0.87, 95% CI, 0.75-1.00; p = 0.044) and lower hematocrit (%, OR, 0.80, 95% CI, 0.74-0.87; p < 0.001) were associated with DFUs. In a subgroup analysis of DFU patients, the PDR group had a longer duration of diabetes mellitus, higher serum BUN, and higher serum creatinine than the non-PDR group. In the multivariable analysis, only higher serum creatinine was associated with PDR in DFU patients (OR, 1.37; 95% CI, 1.05-1.78; p = 0.021).

Conclusions: Diabetic retinopathy is prevalent in patients with DFU and about half of DFU patients had PDR. No significant association was found in terms of the severity of these two diabetic complications. To prevent blindness, patients with DFU, and especially those with high serum creatinine, should undergo retinal examinations for timely PDR diagnosis and management.

Fig 1. Prevalence of diabetic retinopathy (DR) in patients with a diabetic foot ulcer (DFU) and in control diabetic patients without a DFU.

Among patients with a DFU, 90 (90%) had DR and 55 (55%) had proliferative DR (PDR). However, only 16 (0.6%) of 2496 control group patients without a DFU had PDR.

Fig 2. The associations between the Wagner ulcer classification system, ankle-brachial index (ABI), and toe-brachial index (TBI).

(A) The Wagner ulcer classification system and ABI/TBI showed no correlation (p = 0.178 and 0.295, respectively). (B) The ABI and TBI showed a significant correlation (R = 0.573, p < 0.001).

Fig 3. Correlations between the severities of diabetic retinopathy (DR) and diabetic foot ulcer (DFU) or other vascular index.

(A) No correlation was shown between the severities of DR and DFU (R = 0.034, p = 0.734, Pearson’s correlation analysis). The numbers adjacent to the circles indicate sample size. (B) The severity of DR and ABI or TBI value also showed no significant association (p = 0.983 and 0.722, respectively, independent t test).