Submitted by Elliot Bodofsky, MD
Edited by Clark Pinyan, MD
Relative Contributions of Diabetes and Chronic Kidney Disease to Neuropathy Development in Diabetic Nephropathy Patients
. Issar T, Arnold R, Kwai NC, et al, Clinical Neurophysiology 130 (2019): 2088-95.
Distal Symmetric Polyneuropathy (DSP) is a common complication of both Type 2 diabetes (T2DM) and chronic kidney disease (CKD). Diabetic kidney disease (DKD) is the most common cause of CKD. The combination of T2DM and kidney disease (DKD) is believed to cause more rapid progression of neuropathy than either alone, but the relative contributions of DM and renal disease are not clear.
This study recruited 41 normal subjects, 40 with T2DM and normal renal function, 28 with CKD and no DM, and 30 with DKD. The groups were age and gender matched. The two DM groups showed no difference in DM duration, BMI or glycemic control. Renal function matched between the CKD and DKD groups. Patients were evaluated using the 8-point Total Neuropathy Scale (TNS). This includes neuropathy symptoms, physical examination, Sural and Tibial NCS. Median Nerve excitability testing was performed to indirectly assess ion channels, energy-dependent pumps, and axon membrane exchangers.
Patients with DKD had much higher TNS neuropathy scores than patients with T2DM or CKD. T2DM and CKD patients had similar scores. Sural and Tibial NCS showed the greatest abnormalities of any TNS criteria. There were no significant differences between DKD and T2DM and CKD groups in symptoms, but some significant differences in physical exam. Nerve excitability studies also showed that DKD patients had the greatest abnormalities. The DKD excitability pattern was more similar to CKD than TSDM.
T2DM and CKD are very common causes of DSP. The combination, DKD, is unfortunately also quite common in clinical neurophysiology practice. DKD patients often want to know which condition(s) caused their neuropathy. This study shows that both conditions are contributing, although the DKD pattern is a bit more like renal neuropathy. Crucially, the data indicate that NCS assesses the severity of DSP far better than symptoms or physical examination.