How Imeglimin Affects HbA1c

Imeglimin lowers average glucose mainly by amplifying insulin secretion when glucose is high, plus a milder improvement in insulin sensitivity. Over three months that lower average glucose shows up as lower HbA1c.

The complication is the red cell. HbA1c is glucose stuck to haemoglobin, so how much accumulates depends on both average glucose and how long each red cell lives. In the INFINITY trial (29 patients, imeglimin 2,000 mg/day for six months), red cell lifespan lengthened on imeglimin. Older cells collect more glucose, so HbA1c fell more slowly than glycoalbumin and 1,5-anhydroglucitol, which do not depend on red cells. The gap lasted about two months (Osonoi et al., 2025).

• Monotherapy vs placebo (TIMES 1): HbA1c -0.87% at 24 weeks
• Added to metformin (phase 2): -0.44% vs placebo at 12 weeks
• Added to insulin (TIMES 3): -0.60% vs placebo at 16 weeks
• Timing: HbA1c falls gradually and plateaus at around 20-24 weeks, while short-term glucose markers improve within weeks
• In non-diabetic lifters: no data. Expect a much smaller absolute change from a near-normal starting point

All trial populations had type 2 diabetes.

• Baseline: HbA1c, fructosamine, fasting glucose and fasting insulin before starting
• Week 4-6: use fructosamine, not HbA1c. Fructosamine reflects the last 2-3 weeks and is not affected by red cell lifespan
• Week 12 onward: HbA1c becomes useful, but read it alongside fructosamine or fasting glucose
• On TRT or AAS: haematocrit changes, and therapeutic blood donation, also shift red cell age and distort HbA1c. Track haematocrit at the same draw

• If HbA1c barely moves in the first two months but fructosamine and fasting glucose have improved, the drug is probably working; the HbA1c lag is expected
• If fructosamine and fasting glucose have not improved by week 6, imeglimin is not doing much for you
• Do not escalate dose or add drugs based on an early HbA1c alone

Full evidence review: Is imeglimin better than metformin for lifters?