*2.3. Hemoglobin A1c (HbA1c)*

HbA1c levels were measured according to commercial reagen<sup>t</sup> methods (Crystal Chem., Downers, Grove, Elk Grove Village, IL, USA).

## *2.4. Renal Function Test*

Renal function was examined by measurement of urinary albumin/creatinine ratio (ACR), plasma creatinine, and blood urea nitrogen (BUN). To measure the degree of urinary albumin excretion, spot urine samples were collected by bladder massage at the initial (0–4 week), mid (4–8 week), and

late (8–12 week) stages of the experiment. Urinary albumin excretion was determined according to bromocresol green (BCG) albumin quantification method using a commercial albumin assay kit (Bioassay, Hayward, CA, USA). Quantitative urinary creatinine and plasma creatinine levels were measured by Ja ffe method [33]. Levels of BUN were examined using a commercial BUN assay kit (Asan pharmaceutical, Seoul, South Korea) according to the manufacturer's instructions.
