Full mechanism, in text

How the body brings glucose back

1 · What CGM actually measures

A measures glucose in interstitial fluid, which lags blood glucose by 5-15 minutes, so its curve is a delayed mirror of blood glucose. measures interstitial fluid glucose, not blood glucose. There is a 5-15 minute physiological lag — blood changes first, IF follows. The CGM curve is a delayed mirror, not real-time.

It can also be fooled by drugs: after taking acetaminophen (paracetamol), a sensor may report a falsely high glucose value — that is the drug interfering with the sensor, not your glucose actually rising.

2 · Insulin · the brake pedal

When glucose rises, pancreatic β cells secrete insulin, which pulls glucose into muscle and fat and suppresses hepatic gluconeogenesis; it is the only hormone that lowers blood glucose.Rising glucose → pancreatic β cells secrete insulin → ① promotes translocation in muscle/adipose to pull glucose in ② suppresses hepatic gluconeogenesis ③ promotes glycogen synthesis. Insulin is the only hormone that lowers blood glucose.

3 · Glucagon · the gas pedal

When glucose falls, pancreatic α cells secrete glucagon, which makes the liver break down glycogen and start gluconeogenesis; in type 2 diabetes this side fails too.Falling glucose → pancreatic α cells secrete glucagon → ① the liver breaks glycogen down ② gluconeogenesis starts → glucose rises. Insulin and glucagon are two opposing hands in the same organ: insulin holds hepatic glucose output down, glucagon lets it out.

Type 2 diabetes does not only break the β cell: the α-cell side fails too — glucagon does not fall after a meal as it should, so the liver keeps making glucose at exactly the wrong moment. That is why DeFronzo put the α cell in the ominous octet.

4 · What variability means

Healthy glucose stays in a narrow band; large postprandial spikes correlate with oxidative stress and endothelial dysfunction, but their long-term meaning in people without diabetes is debated.Healthy glucose fluctuates within a narrow band (~4-7.8 mmol/L). Large postprandial spikes and rapid swings correlate with oxidative stress and endothelial dysfunction, but long-term clinical significance in non-diabetics is debated — variability ≠ disease risk.

Full mechanism, in text

1 · What CGM actually measures

2 · Insulin · the brake pedal

3 · Glucagon · the gas pedal

4 · What variability means

Glucose regulation · brake & gas

Full mechanism, in text

1 · What CGM actually measures

2 · Insulin · the brake pedal

3 · Glucagon · the gas pedal

4 · What variability means

Glucose regulation · brake & gas