The investigators propose to perform a double-blind, randomized placebo-controlled trial to examine the hypothesis that soy protein with isoflavones could improve glycemic control, insulin sensitivity and decrease cardiovascular risk factors in postmenopausal women with prediabetes.

Inclusion Criteria:

• Hong Kong Chinese menopausal women aged 46-70 years with prediabetes or early untreated diabetes

Exclusion Criteria:

• Women with breast, ovary or other cancers in recent 5-year
• Severe renal or liver dysfunction
• Women with androgen excess
• Smokers
• Current use or recent (3-month)use of any drug or treatment for glycemic control, lipid improvement, weight reduction; Subjects with known soy or milk allergy.