HbA1c — Your Blood Sugar Time-Lapse
The little lab number that doesn’t care how good you were yesterday, only how sugary your life has been on average for months.
HbA1c (glycated haemoglobin) is a measure of how much sugar has been sticking to your red blood cells over time. Glucose in the blood naturally bumps into proteins and forms slow, irreversible attachments; when it bonds to haemoglobin inside red blood cells, we call that HbA1c. Because red blood cells live around 2–3 months, the percentage that end up sugar‑coated reflects your average blood sugar over that window.
In numbers: an HbA1c of about 5% is typical for people without diabetes; around 5.7–6.4% is usually labelled “pre‑diabetes”; 6.5% and above is one diagnostic threshold for diabetes. Each step up isn’t just a cute new label, it reflects more time that tissues are bathing in higher glucose — which is why HbA1c tracks risk for complications like neuropathy, retinopathy and kidney damage.
HbA1c is not perfect. It can be skewed if red blood cells are destroyed faster or live longer than usual (anaemia, some haemoglobin variants), and it doesn’t show how “spiky” your sugar has been — just the average. Two people with the same HbA1c could have very different daily curves: one smooth, one like a rollercoaster. But it’s still an incredibly useful big‑picture marker.
In the world of GLP‑1 medications like semaglutide and tirzepatide, HbA1c is one of the main scoreboard numbers. Trials in type 2 diabetes often ask: how many people got their HbA1c below 7%? How much did it drop compared with other drugs or placebo? These drugs work partly by increasing glucose‑dependent insulin secretion and calming appetite, so less glucose sloshes around to caramelise your haemoglobin in the first place.
Outside of diabetes, HbA1c still shows up in weight‑loss conversations because it tells you how your metabolism is coping with the modern food environment. A falling HbA1c when you change eating patterns, move more, sleep better or start medication is a sign that, on balance, your bloodstream is spending more time in a saner glucose range.
Why It Matters
Compared to one fasting sugar, HbA1c is harder to game. You can’t crash‑diet for 48 hours and magically erase three months of history. That makes it a powerful reality check: it reflects your usual routines, not your best behaviour right before bloodwork.
For people using GLP‑1 medications, HbA1c is one of the clearest ways to see that the drug isn’t just changing the scale, it’s changing how toxic or gentle your average glucose exposure is to blood vessels, nerves and organs.
Closing Line
Think of HbA1c as a time‑lapse of how sweet your blood has been lately — not a single selfie, but a whole montage your body has been quietly filming in the background.