Clinical correlates of sudomotor dysfunction in patients with type 2 diabetes and peripheral neuropathy

Vitamin D deficiency increases the risk of diabetic peripheral neuropathy in elderly type 2 diabetes mellitus patients by predominantly increasing large-fiber lesions

AIMS

This study explores the link between Vitamin D deficiency (VDD) and diabetic peripheral neuropathy (DPN) in elderly type 2 diabetes mellitus (T2DM) patients.

METHODS

Involving 257 elderly T2DM patients, the study utilized propensity score matching to balance age, sex, and diabetes duration. VDD was defined as serum 25-hydroxyvitamin D [25(OH)D] levels below 20 ng/ml. Large nerve fiber lesions were evaluated by electromyogram, while small nerve fiber lesions were assessed by measuring skin conductance.

RESULTS

DPN patients had notably lower serum 25(OH)D levels than non-DPN patients [15.05 vs. 18.4 ng/ml, P = 0.018]. VDD was identified as an independent risk factor for DPN (odds ratio = 2.488, P = 0.008) in multivariate logistic regression analysis. Spearman's correlation showed negative correlations between serum 25(OH)D levels and specific nerve latencies, and positive correlations with specific nerve velocities and amplitudes. The VDD group exhibited longer median sensory nerve latencies and motor evoked potential latencies compared to the vitamin D-sufficient group. Further, VDD is associated with the prolongation of the median motor nerve latency (odds ratio = 1.362, P = 0.038).

CONCLUSIONS

VDD is independently associated with a higher risk of DPN. VDD may promote the development of DPN by affecting large nerve fibers.

Electrochemical skin conductances values and clinical factors affecting sudomotor dysfunction in patients with prediabetes, type 1 diabetes, and type 2 diabetes: A single center experience

BACKGROUND AND AIM

Sudomotor dysfunction is linked to small fibers damage. We investigated sudomotor dysfunction in a large group of participants with diabetes, prediabetes, and nondiabetic healthy subjects. This study aimed to complete knowledge on sudomotor dysfunction in this population, especially regarding the threshold values for the electrochemical skin conductance (ESC) and factors affecting it.

MATERIALS AND METHODS

A total of 690 volunteers in four groups were included in the study (type 1 [T1DG]: n = 80, 61.3% women; type 2 diabetes [T2DG]: n = 438, 63.5% women; prediabetes [Pre-DG]: n = 88, 80.7% women; healthy control [HC-G]: n = 84, 67.5% women). All subjects were investigated for clinical diabetic peripheral polyneuropathy and sudomotor dysfunction. The characteristics of participants obtained from outpatient records were evaluated. We used the Sudoscan device to measure ESC which was normalized for BMI, to improve the discriminative capability of the method.

RESULTS

Diabetic polyneuropathy was found in 17.5% of T1DG, 27.4% of T1DG, and 10.2% of Pre-DG. The mean ESC/BMI was lower in subgroups with diabetic polyneuropathy than those without. Mean ESC/BMI was lowest in T2DG and highest in HC-G but comparable in T1DG and Pre-DG. We accepted the "mean ESC/BMI-1 SD" in the HC-G as the threshold for sudomotor dysfunction. Accordingly, the prevalence of sudomotor dysfunction was 18.8%, 44.3%, 59.1%, and 15% in T1DG, T2DG, Pre-DG, and HC-G, respectively. In T2DG, sudomotor dysfunction was found in 66.7% of persons with retinopathy, of which 56.3% had clinical diabetic polyneuropathy. The prevalence of sudomotor dysfunction in subjects with peripheral artery disease, chronic kidney disease, cardiovascular disease, and hypertension was 46.7%, 47.4%, 43.4%, and 50%, respectively, and 42.9%, 38.9%, 45.5%, and 37.3% of whom in the same order detected with clinical diabetic polyneuropathy. Considering the entire group, a logistic regression model demonstrated that the variables associated with SMD were: retinopathy (OR: 2.969; 95% CI: 1.723, 5.114), female gender (OR: 1.952; 95% CI: 1.287, 2.962), and e-GFR (OR: 0.989; 95% CI: 0.981, 0.998). Since the rate of complications was very low in T1DG, excluding this group, a new model similarly revealed that retinopathy and female gender were associated with SMD, however, the association with e-GFR was disappeared.

CONCLUSION

The prevalence of sudomotor dysfunction is high when established peripheral polyneuropathy was present in diabetes. Even though, sudomotor dysfunction can also occur before clinical polyneuropathy in both types of diabetes (T1DG: 18.8%, T2DG 44.3%), prediabetes (59.1%), and nondiabetic healthy subjects (15%). The variables associated with sudomotor dysfunction were retinopathy and female sex. Normalization of ESC for BMI would be a beneficial approach. However, before this method is included in the routine screening programs for diabetic polyneuropathy, large-scale and prospective studies are required to reach a consensus on the pathological threshold values.

Lower Limb Arterial Ischemia: An Independent Risk Factor of Sudomotor Dysfunction in Type 2 Diabetes

BACKGROUND

As an early manifestation of diabetic peripheral neuropathy (DPN), sudomotor dysfunction significantly increases the risk of diabetic foot ulcer. The pathogenesis of sudomotor dysfunction is still unclear. Lower limb ischemia may be related to sudomotor dysfunction, but few studies have explored it. The purpose of this study is to explore the relationship between sudomotor function and comprehensive lower limb arterial ischemia including large arteries, small arteries and microvascular in type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

511 T2DM patients were enrolled in this cross-sectional study. Sudomotor function was assessed qualitatively and quantitatively by Neuropad. Lower limb arterial ischemia was defined as any abnormality of the ankle brachial index (ABI), toe brachial index (TBI) or transcutaneous oxygen tension (TcPO2).

RESULTS

In this study, 75.1% of patients had sudomotor dysfunction. Compared with normal sudomotor function, patients with sudomotor dysfunction had a higher incidence of lower limb arterial ischemia (51.2% vs 36.2%, p = 0.004). Similarly, compared with the non-arterial ischemia group, the proportion of sudomotor disorders was higher in the arterial ischemia group (p = 0.004). Low TBI and low TcPO2 groups also had a higher proportion of sudomotor disorders (all p < 0.05).Compare with normal groups, low ABI, low TBI, and low TcPO2 groups had lower Slop4 which quantitatively reflecting Neuropad discoloration. Arterial ischemia was an independent risk factor for sudomotor dysfunction [OR = 1.754, p = 0.024]. Low TcPO2 also independently increased the risk of sudomotor disorders [OR = 2.231, p = 0.026].

CONCLUSION

Lower limb arterial ischemia is an independent risk factor of sudomotor dysfunction. Especially below the ankle (BTA) small arteries and microvascular ischemia may also be involved in the occurrence of sudomotor disorders.

Concordance between sudomotor disorder and the clinical diagnosis of diabetic peripheral neuropathy, according to various clinical guidelines

AIM

To assess the concordance between variations in Neuropad® results and the those in different diagnostic criteria of Diabetic Peripheral Neuropathy, according to various clinical guidelines.

METHODS

A descriptive observational study was conducted of 111 patients with a confirmed diagnosis of diabetes mellitus. The criteria for inclusion in the study were that patients should be aged 18 years or more and have at least 10 years' history of diabetes mellitus.

RESULTS

73 (65.8%) were male and 38 (34.2%) were female. Their mean age was 57.92 ± 13.24 years (95% CI 55.45-60.38). Healthy Neuropad® findings were obtained for 35 right feet (31.5%) and 31 left feet (27.9%).

CONCLUSION

Neuropad® is an effective instrument for detecting macro and microvascular complications such as early-stage neuropathy, although its use should always be accompanied by a clinical examination of the foot.

Continuous glucose monitoring defined time-in-range is associated with sudomotor dysfunction in type 2 diabetes

BACKGROUND

Time in range (TIR), as a novel metric for glycemic control, has robust relevance with diabetic complications. Diabetic peripheral neuropathy (DPN) is characterized by sudomotor dysfunction.

AIM

To explore the relationship between TIR obtained from continuous glucose monitoring (CGM) and sudomotor function detected by SUDOSCAN in subjects with type 2 diabetes.

METHODS

The research enrolled 466 inpatients with type 2 diabetes. All subjects underwent 3-d CGM and SUDOSCAN. SUDOSCAN was assessed with electrochemical skin conductance in hands (HESC) and feet (FESC). Average feet ESC < 60 µS was defined as sudomotor dysfunction (+), otherwise it was sudomotor dysfunction (-). TIR refers to the percentage of time when blood glucose is between 3.9-10 mmol/L during 1 d period.

RESULTS

Among the enrolled subjects, 135 (28.97%) presented with sudomotor dysfunction. Patients with sudomotor dysfunction (+) showed a decreased level of TIR (P < 0.001). Compared to the lowest tertile of TIR, the middle and the highest tertiles of TIR was associated with an obviously lower prevalence of sudomotor dysfunction (20.51% and 21.94% vs 44.52%) (P < 0.001). In addition, with the increase of TIR, HESC and FESC increased (P < 0.001). Regression analysis demonstrated that TIR was inversely and independently linked with the prevalence of sudomotor dysfunction after adjusting for confounding values (odds ratio = 0.979, 95%CI: 0.971-0.987, P < 0.001).

CONCLUSION

The tight glycemic control assessed by TIR is of vitally protective value for sudomotor dysfunction in type 2 diabetes mellitus.

The diagnostic usefulness of the combined COMPASS 31 questionnaire and electrochemical skin conductance for diabetic cardiovascular autonomic neuropathy and diabetic polyneuropathy

The study investigated the diagnostic performance for diabetic cardiovascular autonomic neuropathy (CAN) and diabetic polyneuropathy (DPN) of the combined use of composite autonomic symptom score (COMPASS) 31, validated questionnaire for autonomic symptoms of CAN, and electrochemical skin conductance (ESC), proposed for detecting DPN and CAN. One-hundred and two participants with diabetes (age 57 ± 14 years, duration 17 ± 13 years) completed the COMPASS 31 before assessing cardiovascular reflex tests (CARTs), neuropathic symptoms, signs, vibratory perception threshold (VPT), thermal thresholds (TT), and ESC using Sudoscan. Two patterns were evaluated: (a) the combined abnormalities in both tests (COMPASS 31+ESC), and (b) the abnormality in COMPASS 31 and/or ESC (COMPASS 31 and/or ESC). CAN (≥1 abnormal CART) and confirmed CAN (≥2 abnormal CARTs) were present in 28.1% and 12.5%, DPN (two abnormalities among symptoms, signs, VPT, and TT) in 52%, abnormal COMPASS 31 (total weighted score >16.44) in 48% and abnormal ESC (hands ESC <50 μS and/or feet ESC <70 μS) in 47.4%. Both the patterns-COMPASS 31+ESC and COMPASS 31 and/or ESC-were associated with CAN and DPN (P < .01). COMPASS 31 and ESC reached a sensitivity of 75% and 83% for confirmed CAN, and a specificity of 65% and 67% for DPN. When combining the tests, the sensitivity for CAN rose by up to 100% for CAN and the specificity up to 89% for DPN. The combination of the tests can allow a stepwise screening strategy for CAN, by suggesting CAN absence with combined normality, and prompting to CARTs with combined abnormality.