Effects of soy protein and isoflavones on glycemic control and insulin sensitivity: a 6-mo double-blind, randomized, placebo-controlled trial in postmenopausal Chinese women with prediabetes or untreated early diabetes.

Study answer

What this study found

Overall, soy protein with isoflavones and isoflavone supplementation did not produce meaningful improvements in glycemic control or insulin sensitivity versus milk protein placebo. Between-group differences were not significant for fasting glucose (P = 0.8523), 2-hour postload glucose (P = 0.1623), glycated serum protein (P = 0.8793), fasting insulin (P = 0.6983), HOMA-IR (P = 0.6413), HOMA-b (P = 0.5733), or QUICKI (P = 0.9203). A baseline-adjusted sensitivity analysis suggested a marginal 2.34% reduction in 2-hour postload glucose at 6 months (P = 0.077), but this did not change the…

Study & population

This was a 6-month double-blind, randomized, placebo-controlled trial in 180 postmenopausal Hong Kong Chinese women with prediabetes or untreated early diabetes.

Intervention

Participants received either 15 g soy protein plus 100 mg isoflavones daily for 6 months or 15 g milk protein plus 100 mg isoflavones daily for 6 months, compared with a milk protein placebo.

Key limitation

The trial was relatively small, lasted only 6 months, and relied on multiple metabolic endpoints and subgroup analyses, increasing the chance of chance findings.

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Original abstract