Decreased diabetes risk over 9 year after 18-month oral l-arginine treatment in middle-aged subjects with impaired glucose tolerance and metabolic syndrome (extension evaluation of l-arginine study)

What this study found

Long-term l-arginine supplementation was associated with a lower cumulative risk of diabetes over the 108-month study period. Diabetes developed in 40.6% of the l-arginine group versus 57.4% of placebo, with HR = 0.66 (95% CI 0.48, 0.92; p < 0.05), and the incidence rate was 3.0 vs 4.2 per 100 person-years. Benefit was not evident during the 18-month treatment phase itself: 21.4% vs 20.8% developed diabetes during intervention (HR 1.04; 95% CI 0.58-1.86; p = 0.91). During extended follow-up, l-arginine was associated with more favorable trajectories for insulin secretion/sensitivity and…

Study & population

This was a 1:1 randomized controlled study in middle-aged adults with impaired glucose tolerance and metabolic syndrome at a center in Italy.

Intervention

Participants in the active arm received oral L-arginine 6.4 g/day (3.2 g twice daily) for 18 months, compared with placebo.

Key limitation

The trial was relatively small, single-center, and had substantial attrition over long follow-up, which limits precision and generalizability.

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