Distinct Mechanisms Underlie Nerve Damage in Peripheral Neuropathy in Type 1 vs Type 2 Diabetes
Investigators performed 3-tesla magnetic resonance neurography of the sciatic nerve in patients with type 1 diabetes and type 2 diabetes.
The type of sciatic nerve lesions observed in patients with diabetic peripheral neuropathy (DPN) was found to differ in type 1 and type 2 diabetes in a study published in Annals of Neurology. In addition, nerve lesions were associated with impaired glycemic control in type 1 diabetes and with dyslipidemia in type 2 diabetes.
Investigators performed 3-tesla magnetic resonance neurography of the sciatic nerve in patients with type 1 diabetes (n=35) and type 2 diabetes (n=85). A total of 84 patients in this cohort had DPN.
Patients' neuropathic symptoms were assessed using the neuropathy disability score (NDS) and the neuropathy symptom score (NSS). An NDS or NSS score ≥3 and abnormal results of nerve conduction parameters in ≥2 nerves indicated the presence of DPN.
T2-weighted-hyperintense lesion load was found to positively correlate with NSS (P <.0001), NDS (P <.0001), and hemoglobin A1c (HbA1c) (P =.014), and to negatively correlate with tibial compound motor action potential (P <.0001) and peroneal nerve conduction (P =.0002).
T2-weigthed-hypointense lesions were found to positively correlate with NDS (P =.002), NSS (P <.0001), and serum triglycerides (P =.0003), and to negatively correlate with serum high-density lipoprotein (HDL) (P <.0001).
Patients with type 1 diabetes and DPN had a greater T2-weigthed-hyperintense lesion load compared with patients with type 2 diabetes and DPN (19.67%±4.13 vs 12.49%±1.23, respectively; P =.027) and greater levels of HbA1c (8.74%±0.29% vs 7.11%±0.16, respectively; P <.0001).
Patients with DPN and type 2 diabetes vs DPN and type 1 diabetes had a greater volume of T2-weighted-hypointense lesions (27.54 mm2±3.53 vs 19.74 mm2±5.57, respectively; P =.046), higher levels of triglycerides (220.70 mg/dl ±23.70 vs 106.60 mg/dl ±14.51, respectively; P <.0001), and lower levels of HDL (51.29 mg/dl ±3.02 vs 70.79 mg/dl ±4.65, respectively; P <.0001).
Study limitations include the small number of participants and a single patient examination, precluding multivariate and longitudinal analyses.
“Our findings may offer an explanation for the poor effect of glycemic control on the course of DPN in [type 2 diabetes] compared [with] [type 1 diabetes],”the investigators stated.
Jende JME, Groener JB, Oikonomou D, et al. Diabetic neuropathy differs between type 1 and type 2 diabetes: insights from magnetic resonance neurography. Ann Neurol. 2018;83(3):588-598.