*Inclusion criteria*

Probands for this data collection must have type 1 diabetes and either presence or absence of diabetic nephropathy according to the following definitions: Type 1 diabetes is diagnosed if:

Subject had diabetes diagnosed before age 31

Treatment with insulin was instituted within one year of diagnosis

Treatment with insulin has been uninterrupted since diagnosis Presence of diabetic nephropathy is diagnosed if:

Subject with diabetes for at least 10 years has persistent proteinuria or ESRD (not due to condition other than diabetes). Persistent proteinuria is defined as at least 2 of 3 tests positive for albuminuria (at least 1 month apart), i.e., dipstick (Albustix or Multistix) at least 1+ or ACR value exceeding 300 μg albumin/mg of urine creatinine. Absence of diabetic nephropathy is diagnosed if:

Subject has persistent normoalbuminuria despite duration of type 1 diabetes for at least 15 years and has never been treated with ACE inhibitors. Persistent normoalbuminuria is defined as at least 2 of 3 ACR measurements (at least 1 month apart) in random urine specimen being less than 20 μg of albumin/mg of creatinine. If 3 ACR measurements are needed, the highest must also be less than 40 μg of albumin/mg of creatinine.

*Exclusion criteria*

Individuals will be excluded from the study if they do not meet the inclusion criteria described above or if any of the following exclusion criteria are met: Unable or unwilling to give informed consent

Unable to communicate with staff

Major psychiatric disorder such as schizophrenia

Exclusion in relation to medication

Any antihypertensive medication for controls

Infectious disease

Self-reported HIV positivity

Active tuberculosis

Other kidney disease in cases

Alport syndrome

Analgesic nephropathy

Atheroembolic renal disease

Congenital nephrotic syndrome

Focal segmental glomerulosclerosis (FSGS)

Glomerulonephritis

Goodpasture's syndrome

HIV nephropathy

IgM mesangial proliferative nephritis

Lupus nephritis

Kidney cancer

IgA nephropathy

Polycystic kidney disease

Urinary tract infection (Note: infectious processes such as cystitis and urinary tract infections do not represent a permanent exclusion. Patients may be recontacted or asked to send a supplemental urine sample at a later date.)

Pregnant women (although they may be reconsidered 3 months after delivery)