A preliminary study on the combined assessment of 25-hydroxyvitamin D and thyroid function for predicting diabetic...

To examine the disparities in 25-hydroxyvitamin D (25OH-vitD) levels and thyroid function between patients with type 2 diabetic foot (DF) and those with type 2 diabetes(T2DM), and to evaluate the predictive value of 25OH-vitD combined with thyroid function for DF and its impact on amputation.

A total of 79 patients with DF and 79 patients with T2DM were retrospectively enrolled. Data on general information, 25OH-vitD, FT3, FT4, TSH, and other clinical parameters were collected. Statistical analysis was performed using SPSS 27.0.

(1) Compared with T2DM, DF patients had significantly lower serum 25OH-vitD and FT3 levels, and higher prevalence of 25OH-vitD deficiency and euthyroid sick syndrome (ESS). (2) Multivariate logistic regression showed that the deficiency group of 25OH-vitD (<20 ng/mL) had a significantly higher risk of DF (OR = 3.539); the insufficiency group (20-30 ng/mL) showed no significant difference. FT3 was an independent protective factor (OR = 0.493). (3) ROC analysis showed that the AUC for 25OH-vitD alone was 0.620, for FT3 alone was 0.663, and for the combined predicted probability was 0.701. (4) In DF patients, 25OH-vitD was negatively correlated with disease duration and CRP. (5) In DF patients, the ESS group had lower 25OH-vitD levels than the euthyroid group. The amputation rate in the ESS group was 27.3%, significantly higher than that in the euthyroid group (8.8%). The prevalence of ESS in the major amputation group (75%) was higher than that in the minor amputation group (42.9%) and the non-amputation group (23.5%). One-way ANOVA showed significant differences in CRP and TSH among the three amputation groups. Post-hoc analysis indicated that patients with major amputation had significantly higher CRP and TSH levels compared to non- amputation patients. FT3 and 25OH-vitD showed a decreasing trend across the three groups (FT3: P = 0.08, 25OH-vitD: P = 0.13).

In this pilot study, patients with diabetic foot had a higher prevalence of 25OHvitD deficiency and ESS. Combined assessment of FT3 and 25OHvitD showed a trend toward improved prediction of diabetic foot, suggesting the potential value of these markers in evaluating disease severity and prognosis.