Demodex Risk Increased in Patients With Diabetes, Poor Blood Glucose Control

Patients with type 2 diabetes mellitus (T2DM) and poor blood glucose control tend to have a high prevalence of ocular Demodex infestation, according to findings published in Cornea.

The study included 381 patients with T2DM and 163 age- and sex-matched patients without diabetes who were placed in a control group. The researchers collected patient history and demographic data for both groups and performed ocular examination, lash sampling, and microscopic counting of Demodex mites. Patients with T2DM underwent binocular fundus photography. The researchers also gathered blood glucose control status data.

The study shows that the Demodex mite infestation rate were significantly higher in the T2DM patient group than that in the control group (62.5% vs. 44.8%, P <.001). The Demodex count was also higher in the T2D group [median 3 (0–12) vs. 2 (0–9.6), P =.01], especially of Demodex brevis (18.9% vs. 4.9%, P <.001) [0 (0–1) vs. 0 (0–0), P <.001]. Compared with the control group, the T2DM group had a significantly higher ratio of Demodex brevis to Demodex folliculorum (1:3 vs. 1:9, P <.001). Patients with T2DM presented with more cylindrical dandruff (55.1% vs. 39.3%, P =.001).

The study also shows ocular Demodex infestation is strongly associated with poor blood glucose control (HbA1c >7%, P =.2) and is more common in women  (P =.02). The researchers did not identify an association between Demodex infestation and the severity of diabetic retinopathy.

“Poor blood sugar control is a risk factor for ocular Demodex infection in these patients [with T2DM], which stresses the importance of controlling blood glucose in diabetic patients,” the researchers explain.

Study limitations include small sample size and the lack of enrollment of type 1 diabetes patients and younger patients.