Distal Symmetric Polyneuropathy Risk Linked to Diabetes Duration

Patients with longer diabetes duration and higher glycemic exposure have a greater risk of developing distal symmetric polyneuropathy (DSPN), according to study findings published in Diabetes Care. 

Although diabetic DSPN is associated with a high risk for morbidity, limited treatments exist for this condition. Previous research findings suggest that improved glycemic control can lower a patient’s risk of developing DSPN.

To evaluate the effects of diabetes interventions on preventing DSPN, researchers conducted a comprehensive evaluation of the Diabetes Prevention Program Outcome Study (DPPOS; ClinicalTrials.gov; Identifier: NCT00038727), a follow-up study to the Diabetes Prevention Program (DPP; ClinicalTrials.gov; Identifier: NCT00004992). Participants were adults aged 25 years or older who had overweight or obesity, increased fasting glucose levels, altered glucose tolerance, and an increased risk for type 2 diabetes.

At DPP commencement in 1996, participants were randomly assigned to receive metformin 850 mg twice daily or a matching placebo, or an intensive lifestyle intervention. After the study sponsor halted DPP in 2001, participants who consented to participate in DPPOS were offered quarterly intensive lifestyle therapy sessions and the placebo arm was discontinued.

The primary outcome was signs or symptoms of DSPN at year 17 of the DPPOS. The Michigan Neuropathy Screening Instrument (MNSI) was used to evaluate DSPN symptoms. 

The 17-year DPPOS follow-up included 1792 participants, of whom 70.6% were women and 50.9% were White. The average age was 70.4 years (SD, 9.1), average body mass index was 32.1 kg/m² (SD, 6.7), and average time-weighted glycated hemoglobin (HbA_1c) was 6.1% (SD, 0.7).

The overall prevalence of DSPN was 21.7% and did not significantly differ according to the initial DPP treatment assignment.

In the adjusted logistic regression model, the researchers identified no association between DPP treatment and DSPN, but they observed a significant interaction between age and the association between DPP treatment and DSPN (P =.046).  With each 5-year increase in age among participants assigned to intensive lifestyle intervention, the odds ratio [OR] for DSPN decreased by 17.4% (95% CI, 3.0-29.3; P =.019).

The likelihood of DSPN was increased among patients with:

• Diabetes (OR, 1.40; 95% CI, 1.07-1.84; P <.001);
• Increased diabetes duration (OR, 1.04 per year; 95% CI, 1.02-1.05; P <.001); and,
• Higher average HbA_1c (OR, 1.85 per 1% increase; 95% CI, 1.54-2.21; P <.001). 

Study limitations include lack of DSPN data at baseline, survival bias, and the inability to differentiate between secondary causes of peripheral neuropathy. 

“In further studies evaluating the effects of lifestyle interventions on DSPN, the possibility of effect modification by age should be considered,” the researchers concluded. 

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

This article originally appeared on Endocrinology Advisor