Is demodex folliculorum larger in diabetic patients?

To the Editor Demodex folliculorum (DF) which is inhabitant of pilosebaceous follicules has been implicated in rosacea, blepharitis, pityriasis folliculorum, pustular folliculitis, and skin lesions of immunsupressed patients under chemotherapy or with AIDS.1,2 The larval form of DF is a vermiform mite about 0.9 mm long that inhabits the sebaceous glands of the nose, especially the alae nasi, and, to a lesser extent, of the forehead, chin, and scalp.3 Clifford et al.4 found that mites were more abundant in elderly persons, and persons with diabetes. The aim of the present study was to investigate the role of diabetes mellitus on carriage of DF, and to evaluate size of DF in type 2 diabetic patients. Twenty-eight male and 26 female (total 54) patients with type 2 diabetes mellitus without any skin disease, average age of 49.5 ± 13 years, and 54 age- and sex-matched healthy controls without any skin disease and telangiectases were included in the study. Patients with a duration of diabetes under five years were excluded from the study. None of the patients had received any topical or systemic immune supressive drug except oral hypoglycemic agents or insulin for the preceding 2 months. The verbal consent of all subjects was taken for the skin surface biopsies. Initially a red 10 mm square was printed on a microscope slide. After placing a drop of cyanoacrylic adhesive on the other side, it was applied to three different facial sites of the skin for about 1 min. Then it was gently removed and clarified with 2–3 drops of immersion oil and covered with a coverslip. The samples were studied microscopically at same magnifications of × 40 and × 100 in all subjects (fig. 1). Only clearly identified DF were counted and measured with ocular micrometer. The mite density at each facial site, and the sizes of the mites were recorded. The most heavily infested facial region was the cheek in both diabetic patients and control group. The mean mite density on cheeks were 9.636/cm2 in diabetic patients and 4.571/cm2 in the control group; the difference was significant statistically (t = 2.162, P = 0.04). The difference between two groups was not statistically significant in terms of mite positivity and mean mite density at other facial regions (Table 1). Demodex folliculorum obtained by skin surface biopsy technique (original magnification, × 200). The mean mite size in diabetic patients was 1.056 ± 0.022 mm (180 mites) and 0.931 ± 0.047 mm in the control group; the difference between two groups was significant statistically (t = 11.533, P < 0.001). However it has been documented that DF is a resident of pilosebaceous follicules with ambiguous pathogenicity, conflicting results have also been published in many articles related to pathogenicity of this mite.2,6,7 In our study, positivity of DF in diabetic patients was similar to the control group but DF density was found statistically higher in the cheek region of diabetic patients than the control group. Immunsuppressive conditions may cause increasing of density of DF.8 The general effects of hyperglyceaemia are probably important, and there may be additional immune disturbances in diabetes mellitus.9 Although it seems quite probable that immundefence mechanisms may play a protective role by limiting mite numbers, there are also conflicting results. Fortan et al.10 did not find any positive effect of HIV infection on mite density. The mean mite size in diabetic patients was larger than control group statistically. Demodex feeds on sebum and cellular proteins obtained by epithelial and glandular cell destruction through its own enzymatic activity.10 We found a positive correlation between mite and HbA1c percent. HbA1c reflects approximately mean level of blood glucose for last 3 months, therefore, a higher HbA1c level demonstrates a higher mean blood glucose level. This result indicates that increased HbA1c levels may have an effect on the size of mites in diabetic patients. In conclusion; the mean mite density on cheeks is higher in diabetic patients than healthy control group. The mean mite size in diabetic patients is also larger than the control group.