Newly diagnosed type 2 diabetes: the progression and regression of diabetic peripheral neuropathy over 5 years

Aims: This study aimed to examine the progression of DPN over time in a cohort of people with well-regulated and newly diagnosed type 2 diabetes (T2D).

Methods: 389 persons with T2D and 97 controls were included in the study between 2016 and 2018. All participants underwent sensory phenotyping using questionnaires, standard sensory bedside tests, quantitative sensory testing, nerve conduction studies (NCS), and skin biopsies for quantification of the intraepidermal nerve fibre density (IENFD). Participants were classified into possible, probable, and confirmed DPN in accordance with the Toronto consensus. Five years after their initial visit the participants were invited to a follow-up visit using the same examinations and classifications.

Results: 184 of the 389 persons with T2D (47.3%) and 43 of the 97 controls (44.3%) completed their follow-up visit. At baseline, confirmed DPN was present in 35.8% of the persons with T2D, probable DPN in 27.2%, possible DPN in 17.2%, subclinical DPN in 4.6%, and no DPN in 15.2%. At follow-up, confirmed DPN was present in 50.3%, probable DPN in 14.6%, possible DPN in 16.6%, subclinical DPN in 0.7%, and no DPN in 17.9%. The estimated prevalence of confirmed DPN was 22.7% (17.5–28.0) at baseline and 33.5% (24.9–42.1) at follow-up. During the follow-up period, 43.9% of the persons with T2D and probable DPN developed confirmed DPN. Progression occurred in 16.5% and 24.7% and regression in 5.9% and 18.6% based on NCS and IENFD, respectively. The persons that progressed were more likely to have higher baseline waist circumference and higher triglycerides compared to those who did not progress, while the persons that regressed were more likely to have lower baseline HbA1c.

Conclusion: In people with newly diagnosed and well-regulated T2D, the proportion of people with confirmed DPN increased over 5 years mainly driven by progression from probable DPN. A large proportion of people progressed, and a smaller proportion regressed depending on the golden standard applied.

Comments. The present study explores the natural history of DPN progression in a cohort of people with newly diagnosed and well-regulated T2D. The study excels due to its prospective nature and detailed sensory phenotyping, including measures for both large and small fibre neuropathy. The main limitation is the risk of selection bias due the inclusion criteria and the substantial proportion of people with T2D not completing the follow-up. Overall, the study emphasizes the importance of early identification and adequate treatment of T2D and its associated risk factors, as having probable and confirmed DPN 5 years after diabetes diagnosis appears to be associated with progression of DPN across a wide variety of sensory modalities.

Johan Røikjer

Reference. Brask-Thomsen PK, Itani M, Karlsson P, Kristensen AG, Krøigård T, Jensen TS, Tankisi H, Sindrup SH, Finnerup NB, Gylfadottir SS. Development and Progression of Polyneuropathy Over 5 Years in Patients With Type 2 Diabetes. Neurology. 2024 Aug 13;103(3):e209652. doi: 10.1212/WNL.0000000000209652. Epub 2024 Jul 15. PMID: 39008800.

https://www.neurology.org/doi/10.1212/WNL.0000000000209652?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed