Nattokinase’s reputation is built on cardiovascular and circulatory research, which naturally raises the question of whether it helps with diabetes, a condition defined by blood sugar dysregulation but also closely tied to vascular complications. The honest answer splits in two directions: preclinical research on diabetic vascular complications looks genuinely promising, while the actual human evidence on blood sugar itself is unfavorable. This article separates the two rather than blending them into a single vague “supports blood sugar” claim.
Key Takeaways
- A 2023 mouse study found nattokinase protected against diabetic retinopathy complications, improving blood-retinal barrier function and reducing inflammation, independent of blood sugar levels.
- A 2024 rat study found high-dose nattokinase reduced markers of diabetic kidney damage (AGEs, CRP) without lowering blood glucose itself.
- A systematic review and meta-analysis of human randomized controlled trials (607 participants) found nattokinase supplementation showed no significant improvement in blood glucose, and one analysis found a small but statistically significant increase.
- Nattokinase is not a blood-sugar-lowering supplement based on current human evidence, whatever its vascular-complication mechanisms in animal models suggest.
The Vascular-Complication Research: Genuinely Interesting
Diabetes causes complications largely through vascular damage, not just elevated glucose itself, and this is where nattokinase’s preclinical research looks most promising. A 2023 study using a streptozotocin-induced diabetic mouse model found that intravitreal nattokinase administration significantly improved blood-retinal barrier function and rescued pericyte loss (a hallmark of diabetic retinopathy progression), while also inhibiting diabetes-induced gliosis and inflammatory response and protecting retinal neurons from injury[1]. In cell culture, high glucose increased retinal endothelial cell migration (a marker of pathological blood vessel changes), an effect nattokinase pretreatment inhibited in a dose-dependent manner[1].
A separate 2024 study in streptozotocin-induced diabetic rats found high-dose nattokinase significantly inhibited increases in circulating advanced glycation end products (AGEs, a marker linked to diabetic tissue damage) and reduced C-reactive protein (an inflammation marker), alongside reduced glycogen deposition in renal tubules, notably without downregulating blood glucose levels itself[2]. That last detail is important: the protective effects observed appear to work through anti-inflammatory and anti-glycation mechanisms independent of any blood-sugar-lowering action.
The Human Blood Sugar Evidence: Not Favorable
A systematic review and meta-analysis of randomized controlled trials, covering 607 participants, evaluated nattokinase’s effects on cardiovascular risk factors. It found nattokinase supplementation showed no significant improvement in blood lipids or blood glucose overall, and a further analysis within that review found nattokinase supplementation was actually associated with a small but statistically significant increase in blood glucose compared to placebo, along with higher total cholesterol in high-dosage groups[3]. The same review did find a beneficial effect on blood pressure, so the picture is mixed rather than uniformly negative, but the specific claim “nattokinase supports healthy blood sugar” is not supported by this human trial evidence, and the data leans mildly the other direction.
Reconciling the Two Findings
These aren’t necessarily contradictory studies; they’re measuring different things. The animal research shows nattokinase may reduce inflammatory and glycation-related tissue damage in diabetic models without changing glucose levels, essentially a vascular-protection mechanism that operates downstream of blood sugar control rather than a glucose-lowering mechanism. The human meta-analysis measured glucose and lipid levels directly and found no benefit there, consistent with the animal data’s own finding that nattokinase didn’t move glucose in those models either. Neither body of evidence supports using nattokinase to manage blood sugar, and the human data suggests some caution around glucose in high-dosage use.
Practical Considerations
Anyone with diabetes considering nattokinase for cardiovascular or circulatory reasons should discuss it with their physician, disclose their full medication list (particularly if on insulin, other glucose-lowering medications, or anticoagulants, since diabetes and cardiovascular medication regimens frequently overlap with nattokinase’s own interaction profile), and should not substitute it for prescribed diabetes management or expect it to improve glucose control based on current human evidence.
References
- Huang et al. Protective effects of nattokinase against microvasculopathy and neuroinflammation in diabetic retinopathy. Journal of Diabetes (2023). PMID 37403338
- Effect of nattokinase on the pathological conditions in streptozotocin induced diabetic rats. Heliyon (2024). PMC10998082
- Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Reviews in Cardiovascular Medicine (2023). PMC11266782
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.
