Low serum sodium levels are associated with diabetic peripheral neuropathy (DPN) regardless of the results of a retrospective study published in the Journal of Diabetes Research, even within the normal serum sodium range in patients with type 2 diabetes (T2D).
Currently, the literature on the relationship between DPN and serum sodium levels is limited.
In the current cross-sectional study, the researchers tried to clarify this relationship in order to enable early screening in patients with T2D.
Patients with T2D were admitted to a single medical center between 2010 and 2018. The diagnosis of diabetes was made based on the criteria of the World Health Organization (WHO), and hypertension was rated as a systolic blood pressure of 140 mmHg or higher or a diastolic blood pressure of 90. defines mmHg or higher. Corrected blood sodium levels were calculated based on blood sugar levels.
Somatic neuropathy symptoms were documented; These included numbness, burning, deep pain, and insecurity while walking. Neurological examinations were completed and the neurological score and reflex score and sensory function value were recorded. In addition, the patients were subjected to a nerve conduction study.
The study cohort included 1928 patients with T2D (mean age 60.10 years; 1,053 men) enrolled from the Department of Endocrinology and Neurology at the First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, China. Within the cohort, 1,530 had normal serum sodium levels, 342 had hypernatremia, and 56 had hyponatremia. In addition, a total of 960 participants were diagnosed with DPN.
Patients were divided into 3 groups based on diagnostic criteria (hyponatremia, hypernatremia, and normal serum sodium); the normal serum sodium group was further divided into 3 tertiles.
Significant changes were observed in terms of gender, body mass index (BMI), smoking status, alcohol consumption, and use of diuretics and oral anti-diabetic drugs.
Regarding nerve conduction function, the researchers found that motor and sensory nerve conduction velocity and sensory nerve action potential (SNAP) of the ulnar and sural nerves increased with an increase in serum sodium. The action potential of the tibia and peroneal nerve muscles as well as the superficial peroneal nerve SNAP increased and then decreased again. Among the patients with normal serum sodium levels, those in the low-normal versus high-normal tertile had lower mean corpuscular volume, lower sensory conduction velocity (SCV) of the ulnar nerve, and SCV of the superficial peroneal nerve.
The DPN risk was “relatively flat” up to a serum sodium level of 140 mmol / L (95 mg / dl), with the risk increasing rapidly in all serum sodium groups – especially in men under 65 years of age and those with urine albumin-to-creatinine- Ratio (UACR) less than 30 mg / g.
In a full group analysis, the researchers divided the patients into 5 groups based on serum sodium levels. The results of multiple logistic regression analyzes showed that hyponatremia was associated with DPN after adjusting for several factors such as age, gender, duration of diabetes, BMI, blood pressure, hemoglobin A1c, and estimated glomerular filtration rate; Use of antihypertensive or hypoglycemic drugs or insulin; and smoking, drinking and high blood pressure. Across all serum sodium groups, no significant association was found between subsets of participants 65 years of age or older or with a UACR of at least 30 mg / g.
A fully adjusted logistic regression analysis in the group with normal serum sodium showed that a high normal serum sodium level was a “relatively lower” risk factor for DPN (odds ratio 0.690; 95% CI 0.526-0.905; P = 0.007). This association was particularly noticeable in men, participants under 65 years of age, people with diabetes duration of less than 10 years, and people with a UACR of less than 30 mg / g.
Limitations of the study included the small number of patients with hyponatremia, the lack of recorded sodium intake and vitamin B levels, and the inability to determine whether the relationship between DPN and hyponatremia “reflects a direct effect of hyponatremia, a surrogate marker for underlying comorbidities or reasons “for DPN or both.”
“Since even minor disturbances in serum sodium are linked to mortality, frequent monitoring of electrolytes and stopping medication with side effects if needed can greatly improve patient outcomes,” the researchers concluded. “Further studies are needed to understand the factors leading to this prognostic association and the potential benefits of therapeutic strategies targeting this metabolic disorder.”
Y. Zhang, C. Li, L. Huang, et al. Relationship between hyponatremia and peripheral neuropathy in patients with diabetes. J Diabetes Res. Published online August 20, 2021. doi: 10.1155 / 2021/9012887
This article originally appeared on Clinical Pain Advisor