Association of Cardiovascular Autonomic Neuropathy and Distal Symmetric Polyneuropathy with All-Cause Mortality: A Retrospective Cohort Study

The handgrip test - A historical test for diabetic autonomic neuropathy or a marker of something else?

Cardiovascular autonomic neuropathy (CAN) is a frequent complication of diabetes mellitus and is associated with increased morbidity and mortality in patients with diabetes. Hence, early and correct diagnosis of CAN is crucial. Standard cardiovascular reflex rests (CARTs) have been the gold standard of CAN assessment. Originally, CARTs consisted of five reflex tests, but measuring diastolic blood pressure response to sustained handgrip exercise has no longer been suggested as an established clinical test. Increasing body of evidence suggests that isometric handgrip test should no longer be used for the evaluation of sympathetic dysfunction during cardiovascular autonomic neuropathy assessment in diabetic patients. The associations of isometric handgrip test results with parameters of hypertension and markers of hypertension-related target-organ damage in diabetic and non-diabetic individuals point toward its potential role as a screening tool to identify patients with high cardiovascular risk. The current review summarizes historical view of standard cardiovascular reflex tests and latest data on isometric handgrip test.

No clear evidence of neuropathy among patients with high risk for the development of prediabetes/diabetes-a pilot study

Introduction

Autonomic and sensory neuropathy have been observed in both prediabetes and manifest diabetes mellitus. However, there is a lack of available data regarding whether patients at a moderate or high risk of developing diabetes, yet without a current diagnosis of prediabetes or diabetes, exhibit an increased prevalence of neuropathy.

Methods

FINDRISC (Finnish Diabetes Risk Score) was used to classify individuals at risk (≥12 points, n = 44; control <12 points, n = 28). HbA1c levels >5.6% served as exclusion criteria, and patients with known medical conditions predisposing to neuropathy were also excluded. Cardiac autonomic function (Ewing tests) and peripheral sensory neuropathy (Neurometer and Q-sense) were assessed by standardized protocols, and their potential association with increased FINDRISC points was analyzed using a regression model.

Results

Mean age was 46.7 ± 14.3 years in the control and 55.7 ± 14.1 years in the increased risk group. Male/female ratio did not differ. Individuals with increased risk of diabetes were more obese (BMI: 29.9 ± 12.5 kg/m2 vs. 25.9 ± 8.9 kg/m2). Additionally, hypertension was more frequent among them (68.2% vs. 17.9%), and their lipid parameters were also less favorable. Parasympathetic neuropathy was present in both groups (56.8% vs. 32.1%, respectively). Sympathetic neuropathy was not found. Sensory nerve dysfunction was of low prevalence in the high-risk group and did not occur in healthy controls. In multiple logistic regression analysis, HbA1c exhibited an independent association with parasympathetic neuropathy (OR: 5.9; 95% CI: 1.08-32.68; p < 0.041).

Discussion

An increased risk of developing prediabetes/diabetes does not appear to have a strong correlation with an increased likelihood of developing autonomic or sensory neuropathy. However, the etiology behind the occurrence of parasympathetic autonomic neuropathy in healthy individuals remains unknown.

The association between distal symmetric polyneuropathy in diabetes with all-cause mortality - a meta-analysis

BACKGROUND

Distal symmetric polyneuropathy (DSPN) is a common microvascular complication of both type 1 and 2 diabetes with substantial morbidity burden and reduced quality of life. Its association with mortality is equivocal.

PURPOSE

To describe the association between DSPN and all-cause mortality in people with diabetes and further stratify by the type of diabetes based on a meta-analysis of published observational studies.

DATA SOURCES

We searched Medline from inception to May 2021.

STUDY SELECTION

Original data were collected from case-control and cohort studies that reported on diabetes and DSPN status at baseline and all-cause mortality during follow-up.

DATA EXTRACTION

was completed by diabetes specialists with clinical experience in neuropathy assessment.

DATA SYNTHESIS

Data was synthesized using random-effects meta-analysis. The difference between type 1 and 2 diabetes was investigated using meta-regression.

RESULTS

A total of 31 cohorts (n=155,934 participants, median 27.4% with DSPN at baseline, all-cause mortality 12.3%) were included. Diabetes patients with DSPN had an almost twofold mortality (HR: 1.96, 95%CI: 1.68-2.27, I2 = 91.7%), I^{2 =} 91.7%) compared to those without DSPN that was partly explained by baseline risk factors (adjusted HR: 1.60, 95%CI: 1.37-1.87, I^{2 =} 78.86%). The association was stronger in type 1 compared to type 2 diabetes (HR: 2.22, 95%CI: 1.43-3.45). Findings were robust in sensitivity analyses without significant publication bias.

LIMITATIONS

Not all papers reported multiple adjusted estimates. The definition of DSPN was heterogeneous.

CONCLUSIONS

DSPN is associated with an almost twofold risk of death. If this association is causal, targeted therapy for DSPN could improve life expectancy of diabetic patients.

Skin advanced glycation end products as a screening tool of neuropathy in type 2 diabetes mellitus

AIM OF THE STUDY

To examine the diagnostic utility of skin advanced glycation end products (AGEs) as screening tool of neuropathy in type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

We included 132 participants (88 men) with a mean age of 64.57 years and median T2DM duration of 14.5 years. Skin AGEs were measured with AGE reader mu connect (Diagnoptics) on the dominant arm and were interpreted as normal vs. elevated. Distal sensorimotor polyneuropathy (DSPN) was diagnosed by the Neuropathy Disability Score. Cardiovascular autonomic neuropathy (CAN), sympathetic and parasympathetic nervous system impairment were diagnosed by cardiovascular autonomic reflex tests.

RESULTS

For DSPN, AGEs yielded high sensitivity (82.8%) and NPV (80.4 %) with moderate specificity (55.4 %). For CAN, they yielded relatively high sensitivity (75.0 %) and NPV (74.5 %) with low specificity (48.7 %). For sympathetic nervous system impairment, AGEs yielded relatively high sensitivity (75.0 %) and high NPV (84.3 %) with low specificity (43.9 %). For parasympathetic nervous system impairment, they yielded high PPV (81.0 %) with moderately high sensitivity (66.7 %) and moderate specificity (55.9 %).

CONCLUSIONS

In a simplified approach, skin AGEs may be used as a screening tool of DSPN and CAN (including sympathetic and parasympathetic nervous system impairment) in T2DM.