Are All Whole Grains Equal for Blood Sugar?

Not quite. A new trial suggests that grain structure matters: less-processed whole grains modestly improved a long-term blood sugar marker compared with finely milled whole grains.

What was tested?

In New Zealand, 160 adults with type 2 diabetes, averaging 58.5 years old, were assigned whole grain foods with different levels of processing for 12 weeks. Both groups received wheat, rice and oats.

How big was the difference?

The October 26, 2026 study found HbA1c was 2.2 mmol/mol lower with less-processed grains—about 0.2 percentage points. Weight change did not differ between groups. This was a small benefit, not a dramatic metabolic reset.

What belongs on your shopping list?

Look beyond “whole grain” to the food itself. Brown rice and intact oat groats offer alternatives to flour-based staples. The trial tested a bundle of foods, so it cannot credit one grain or promise the same benefit without diabetes.

For a busy week, try one less-processed grain as a familiar meal’s side. Keep diabetes treatment decisions with your care team.

Source: Reynolds et al., AJCN (2026).