Sub-Clinical Peripheral Neuropathy in Indian Adolescents with Type 1 Diabetes: Estimation of Prevalence and Modifiable Risk Factors.

Introduction: Clinical screening for diabetic neuropathy diagnoses only the tip of the iceberg and may miss sub-clinical neuropathies whose progression can be prevented/reversed if detected early. Hence, this study was conducted to compare nerve conduction (NCS) parameters of adolescents with type 1 Diabetes (T1D) with healthy controls and to assess prevalence and risk factors for sub-clinical peripheral neuropathy in Indian adolescents with T1D. Methods: Case-control study. Cases (n = 120): 10-19 years, T1D duration >2 years. Exclusion: Comorbidities/illnesses/medication affecting nerve function. Controls (n = 40): Healthy, age, sex-matched. Results: Mean age: 15.1 ± 3 years; diabetes duration: 7 ± 3.5 years, HbA1c: 9.6 ± 2.1%. None had symptoms/signs of peripheral neuropathy. NCS comparison demonstrated significantly prolonged latency, reduced action potential duration, and nerve conduction velocity (P < 0.01) in motor nerves (median, ulnar, peroneal, tibial) in patients with T1D. Sensory action potential duration in median and ulnar nerves, and sural conduction velocity were significantly lower in T1D (P < 0.05). 26.7% had at least one abnormal NCS parameter. Sub-clinical neuropathy prevalence- demyelinating motor: upper limbs (UL)-5.8%, lower limbs (LL)-11.7%; demyelinating sensory: UL-5.0%, LL-5.0%; axonal motor: UL-4.2%, LL-2.5%; axonal sensory: UL-2.5%, LL-5.0%. Six (5.0%) had stage-1a distal symmetrical polyneuropathy. HbA1c (OR = 1.5), age (OR = 1.4), female gender (OR = 0.2), iron intake (OR = 0.8), and hypertension (OR = 19.7) were significantly associated with sub-clinical neuropathy. Conclusion: The prevalence of sub-clinical peripheral neuropathy in Indian adolescents with T1D was considerable, with the highest prevalence observed in the lower limbs. Despite no symptoms, NCS parameters were adversely affected in T1D, highlighting the need for early NCS-based screening. Poor glycaemic control, reduced iron intake, and hypertension were modifiable risk factors associated with sub-clinical neuropathy, apart from non-modifiable factors like male gender, age.