Pathogenesis of Kidney Disease in Type 1 Diabetes: a Modern Kidney Biopsy Cohort (The PANDA Study)

Inclusion Criteria: * Age ≥ 18 years at enrollment (rationale: this study focuses on determinants of early DKD over the course of T1D in adults) * T1D duration \>5 years (rationale: DKD in T1D rarely manifests prior to 5 years of disease duration) * HbA1c \<11% (rationale: HbA1c ≥ 11% exceeds the average HbA1c at most academic center and would limiting the generalizability of our study findings) Exclusion Criteria: * T2D and monogenic diabetes (rationale: our study focuses on T1D) * Recent diabetic ketoacidosis, i.e., \<1 month (rationale: safety and insulin resistance and tubular dysfunction of DKA can confound study findings) * eGFR \< 30 ml/min/1.73m2 or dialysis treatment (rationale: to reduce the likelihood of identifying secondary pathways that are not specific to kidney injury from T1D) * Kidney transplant recipients (rationale: molecular confounding from immunosuppression) * Kidney biopsy contraindications (rationale: safety - kidney biopsy): * Evidence of bleeding disorder or complications from bleeding * Use of aspirin, Nonsteroidal anti-inflammatory drugs (NSAIDS) or other blood thinner that cannot be safely stopped for a sufficient time before and after the biopsy to avoid additional risk of bleeding. * INR \> 1.4 * Hemoglobin (Hgb) \< 10 mg/dL (Colorado) \[altitude\] * Hemoglobin (Hgb) \< 9 mg/dL (Washington) * Platelet count \< 100,000 / µL * Uncontrolled or difficult to control hypertension (\> 150/90 mmHg at the day of biopsy) * Single kidn…