Hypothesis: High doses of vitamin D (VitD) improves dermal microcirculation (MC) in diabetic patients with type 2 diabetes mellitus (T2DM) and diabetic neuropathy (DN).
Purpose: To study the effect of different VD doses on skin MC values in T2DM patients and DN.
Materials and methods: Sixty-two non-smoking T2DM patients with DN were randomized into two groups: Group 1 received 5000 IU (G1) and Group 2 received 40000 IU (G2) of cholecalciferol per week. Inclusion criteria included HbA1c up to 9.0%, neuropathy disability score (NDS) of 4 and higher. MC parameters (value of perfusion M, standard deviation of blood flow σ and Kv - coefficient of microcirculation, %) were assessed by Laser Doppler Fluorometry (LDF) (LAKK-M, Russia); two functional tests: postural (blood flow reduction rate was calculated - BFR) and occlusion (capillary blood reserve index was calculated - CBR), 25(OH)D were studied at baseline and after 24 weeks. The MC values of control healthy subjects (Group 3; G3) were used for comparison.
Results: The clinical characteristics of patients werecomparable (G1: n=31; age 52.4±5.7, BMI 30.2±4.3; serum 25(OH)D 28.0±16,9 (units); HbA1c 7.6±0.8% and G2: n=31; age 51.4±6.1; BMI 31.1±4.5; serum 25(OH)D 23.9±7.9; HbA1c 7.7±0.9%; (P>0.05). G3 (n=16; age 51.8±3.7; BMI 30.1±2.7, 25(OH)D 29.11±13.6) only difference was HbA1c level (4.8±0.5%; P=0.001). The MC parameters in T2DM pts were significantly lower than in G3 (MG1+2=7.2±0.8, & MG3=10.4±5 (P=0.007); σG1+2=3.1±0.4 & σG3=4.2±0.6 (P=0.013); KvG1+2 35.2±15.1 & KvG3=40.3±14.5 (P=0.003) respectively. No changes of MC were seen in G1 after treatment (M=6.9±0.5 & M=7.3±0.4; σ=3.5±0.6 & σ=4.4±0.8; Kv 34.7±13.2 & Kv=35.2±14.1 (P>0.05). In G2 HbA1c decreased, 25(OH)D increased, all parameters of MC improved (M=7.3±0.6, & M=8.7±0.9 (P=0.003); σ=3.4±0.3 & σ=5.3±0.7 (P=0.005), Kv=36.8±11.7 and Kv=38.1±12.1 (P=0.008). The postural test was more informative due to good portability and ease of implementation and revealed lower baseline BFR in pts compared to G3 (P=0.027). Positive correlation between BFR, CBR and 25(OH)D after treatment was find only in G2 (r=0.72, P=0.03 & r=0.85, P=0.02, respectively).
Conclusions: High dose of VitD supplementation (40,000 IU/week) for 6 months in T2DM patients with DN was associated with HbA1c decrease and improvement in microcirculation parameters.
18 - 21 May 2019
European Society of Endocrinology