Inclusion Criteria:
* Participants must be at least 18 years of age and able to provide informed consent.
* Chronic spinal cord injury (at least 1 year post-injury) with neurological level of injury T6 or above, classified as AIS A-D, or able-bodied individuals without a history of spinal cord injury or neurological disorder
* Participants must meet criteria for normal glucose metabolism, prediabetes, or type 2 diabetes, determined using HbA1c, fasting plasma glucose, fasting insulin, or oral glucose tolerance testing (OGTT). Normal glucose metabolism is defined as HbA1c less than 5.7% and fasting plasma glucose less than or equal to 100 mg/dL. Impaired glucose metabolism (prediabetes or type 2 diabetes) will be identified by HbA1c greater than or equal to 5.7%, fasting plasma glucose greater than100 mg/dL (5.6 mmol/L), fasting insulin greater than 8.5-10 µIU/mL after at least 8 hours of fasting, or 2-hour plasma glucose greater than 140 mg/dL (7.8 mmol/L) during a standard OGTT performed using a 75 g anhydrous glucose load dissolved in water.
* Participants taking diabetes medications may be included if their medication regimen has been stable for at least 12 weeks before enrollment. This ensures observed metabolic changes are attributable to tSCS rather than recent medication adjustments. Medication use will be documented and included as a covariate in analyses to account for potential effects
Exclusion Criteria:
* Unstable medical conditions (e.g., cardiac disease, active infections).
* Implanted devices (e.g., pacemakers, neurostimulators, ITB pumps).
* Change of medications that alter glucose metabolism (e.g., corticosteroids).
* Frequent, symptomatic hypoglycemia.
* Inability to tolerate stimulation procedures or complete study protocols.
* Diagnosis of Type 1 diabetes mellitus.
* Skin breakdown, eczema, or other dermatological conditions (e.g., psoriasis) affecting the skin at the site of electrodes placement.
* Females who are pregnant, breastfeeding, or intend to become pregnant.
* Cognitive impairments, social/psychological problems, or other comorbid conditions that, in the opinion of the Investigator, will preclude them from participation.
