Here is the design of a clinical trial:

Official Title: Intervention Using Vitamin D for Elevated Urinary ALbumin in Diabetes (IDEAL-2)

Included conditions:
- Diabetic Nephropathies

Study Armgroups:
- {'label': 'Intervention Group', 'type': 'EXPERIMENTAL', 'description': 'Participants are treated with angiotensin converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB) AND active vitamin D (Calcitriol) 0.25 micrograms orally per day for 26 weeks.', 'interventionNames': ['Drug: Calcitriol']}
- {'label': 'Usual Care', 'type': 'NO_INTERVENTION', 'description': 'Participants are treated with ACEI/ARB alone for 26 weeks.'}

Interventions:
- {'type': 'DRUG', 'name': 'Calcitriol', 'description': 'Active vitamin D (Calcitriol) 0.25 micrograms', 'armGroupLabels': ['Intervention Group'], 'otherNames': ['Active Vitamin D']}

Primary Outcomes:
- {'measure': 'Urinary albumin creatinine ratio (ACR) measured biochemically', 'description': 'Urine albumin and creatinine will be measured biochemically and their ratio calculated', 'timeFrame': '26 weeks'}

Please estimate the sample size based on the assumption: 
power of 80%, significance level (α) of 0.05, and a potential dropout rate of 20%
Sample size calculations
        A sample size of 320 individuals will be enrolled in the study. Based on the VITAL study, we estimate a treatment effect for albuminuria of dâ=â0.25 sd and an intraclass correlation coefficient of 75% for our current study. To achieve a power of 80% to detect a statistically significant treatment effect for a two-tailed test with Î±â=â0.05, we calculate a minimum of 256 participants. To cater for a potential dropout of 20%, we will enrol a total of 320 individuals.