Increased kidney volume (KV) and Na-Li CT have been proposed as markers of glomerular hypertrophy/hypertension in short-term IDDM. Both have been associated with metabolic control, although a genetic component has also been suggested for Na-Li CT. This study used a cross-over design to examine the separate effects of Enalapril (EN) and Intensive Diabetes Therapy (IDT) on KV and Na-Li CT in IDDM. 17 subjects were recruited from a cohort shown on ultrasound screening to have increased KV (> 275 ml/1.73 m2) (7M, 10F; mean age 15.5±4.0 (SD) yrs; IDDM duration 7.4±1.7 yrs; HbA 1c 9.4±1.0%). Subjects were randomly assigned to 3 months of EN (0.25 mg/kg/day) or IDT (4 insulin injections per day with daily adjustments of insulin dose based on preprandial blood glucose (target 4-7 mmol/L), diet and exercise). The washout period was 3 months, followed by 3 months of the alternate treatment. Na-Li CT was measured in red blood cells and expressed as mmol/L RBC/hour (normal < 0.4). There was no treatment order or carryover effect so the intervention groups were combined independent of order. During IDT, there was a significant decrease in mean HbA 1c (*p<0.0001), while there was no change in HbA 1c with EN. Neither intervention altered KV significantly. Although EN had no effect on Na-Li CT, there was a significant decrease in Na-Li CT during IDT (**p=0.006). This extends previous reports linking Na-Li CT with metabolic control and suggests that Na-Li CT may be a risk factor modifiable by IDT. The lack of change in KV may be due to the short intervention period and/or methodologic issues and warrants further investigation. Table

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