Older age, insulin use, stroke linked to diabetic peripheral neuropathy in T2DM

Diabetic peripheral neuropathy (DPN) is not uncommon among patients with type 2 diabetes mellitus (T2DM) in Singapore and is significantly associated with increased age, Indian ethnicity, insulin use, diabetic retinopathy, and stroke, according to a recent study.

“Early identification and increased understanding of risk factors and comorbidities allow clinicians to develop targeted screening of DPN and implement strategies to help to prevent diabetic foot ulcers and their complications,” the researchers said.

This retrospective analysis was conducted for 1 year at Ng Teng Fong General Hospital and included patients who underwent diabetic foot screening and endocrinologist review in the Diabetes and Endocrinology Specialist Outpatient Clinic during the period January 2019–December 2019.

DPN was defined by the patient’s inability to detect at least one of 10 sites using the 10 g monofilament. Multivariable logistic regression was used to assess risk factors significantly associated with DPN.

A total of 479 patients were included in the analysis. DPN had a prevalence of 28 percent (95 percent confidence interval [CI], 24.0–32.2). [Proc Singap Healthc 2021;30:265-270]

The following risk factors were significantly associated with DPN: age >65 years (odds ratio [OR], 5.44, 95 percent CI, 2.87–10.32), Indian ethnicity (OR, 1.99, 95 percent CI, 1.04–3.80), insulin use (OR, 1.65, 95 percent CI, 1.03–2.64), diabetic retinopathy (OR, 2.36, 95 percent CI, 1.47–3.78), and stroke (OR, 2.44, 95 percent CI, 1.03–5.77).

Duration of diabetes was not a significant risk factor for DPN, but previous studies showed that it was significantly associated with higher risks of DPN among diabetic patients. [PLoS One 2019;14:e0212574; Diabetol Metab Syndr 2012;4:21; J Diabetes Investig 2014;5:714-721; Rev Diabet Stud 2015;12:48-62]

The finding of the current study might have been affected by the limited accuracy of this independent variable during data extraction and collection.

“As this study is a retrospective analysis of medical records, another limitation is that it can only highlight the associations between risk factors, and causality cannot be determined,” the researchers said. “Additionally, the findings are limited by the validity and completeness of data.”

The sensitivity and specificity of the 10 g monofilament test was also varied and dependent on the number of sites being tested on the foot. The current study tested 10 sites on each foot with the monofilament. [Diabetes Res Clin Pract 2010;90:1-7]

Published in June 2019, the Ministry of Health Singapore Appropriate Care Guide on foot assessment in patients with diabetes recommends the use of monofilament on four sites on each foot (the plantar aspect of the hallux and the heads of the first, third, and fifth metatarsals). [https://www.ace-hta.gov.sg/our-guidance/foot-assessment-in-people-with-diabetes.html]

However, a study by Zhang and colleagues found no significant differences in the effectiveness between both four- and 10-site monofilament testing for DPN screening. [J Int Med Res 2018;46:3278-3284]

“Furthermore, the estimated prevalence of DPN in this study is to be interpreted with caution, as the study sample mainly represented patients with a low to medium risk of developing foot complications or lower-extremity amputation due to their T2DM,” the researchers said.

“Despite its limitations, this study is still useful as it adds to the limited body of research in Singapore regarding the prevalence of DPN and its risk factors in T2DM patients,” they added.