Insulin, Resistance, and the Crisis of Ketoacidosis

When the Key No Longer Fits the Lock

Every cell in your body runs on glucose. Insulin is the key that unlocks the door — binding to receptors on the cell surface and triggering transporters (GLUT4) to open and let glucose in. In a healthy person, this happens within minutes of eating. Blood glucose rises, the pancreas releases insulin, and cells absorb the sugar they need to function.

In diabetes, this elegant system breaks down — but in two very different ways depending on the type.

Type 2 Diabetes: The Lock Stops Responding

In Type 2 diabetes, the pancreas still produces insulin — often in large amounts — but the cells have become desensitised to it. The receptor is present, but it no longer responds normally to insulin's signal. Glucose builds up in the blood while the cell goes hungry. The pancreas compensates by producing even more insulin, which eventually exhausts the beta cells and makes the resistance worse.

This desensitisation is driven primarily by chronic overexposure to glucose and insulin — years of high-carbohydrate eating that keeps both perpetually elevated. Fat accumulation inside liver and muscle cells also blocks the signalling cascade that insulin depends on.

Insulin Injection: Overriding the Resistance

When oral medications are no longer sufficient, injected insulin can restore glucose uptake by flooding the system with enough signal to overcome the desensitised receptors. It is a workaround, not a cure — the underlying resistance remains, and doses typically need to increase over time. For Type 1 diabetes, where the pancreas produces no insulin at all, injection is not a workaround but a life-sustaining necessity from diagnosis onward.

Diabetic Ketoacidosis: When the Body Burns Its Own Fat to Survive

Without any functional insulin — most commonly in untreated or undertreated Type 1 diabetes — the body faces a crisis. Cells cannot absorb glucose no matter how high blood sugar climbs. The body interprets this as starvation and activates an emergency response: it begins breaking down fat.

The liver converts the released fatty acids into ketone bodies — acetoacetate, beta-hydroxybutyrate, and acetone. In small amounts, ketones are a normal and healthy alternative fuel. But in DKA, they are produced far faster than the body can use or excrete them. They accumulate in the blood, and because they are acids, the blood pH drops — from the normal 7.35–7.45 into dangerously acidic territory below 7.3. This is diabetic ketoacidosis.

DKA is a medical emergency. Left untreated, the acidic blood disrupts enzyme function throughout the body, impairs cardiac and neurological function, and can be fatal within hours to days. The breath takes on a distinctive fruity or nail-polish odour from acetone being exhaled.

Why DKA Happens — The Short Version

• No insulin → cells cannot absorb glucose → blood glucose spikes
• Glucagon surges (the counter-hormone to insulin) → signals fat cells to release fatty acids
• Liver converts fatty acids into ketone bodies at high speed
• Ketones accumulate faster than kidneys can excrete them → blood acidifies
• Result: blood pH below 7.3, fruity breath, vomiting, rapid deep breathing, confusion, coma

DKA is treated with IV insulin (which shuts down ketone production immediately), IV fluids to rehydrate and dilute the acid load, and careful electrolyte replacement — particularly potassium, which shifts dramatically as insulin drives glucose and potassium back into cells.

The Metabolic Thread

Both insulin resistance and DKA are, at their root, disorders of the same system — the machinery that moves glucose from blood into cells. In Type 2 diabetes the machinery is jammed by chronic overconsumption. In Type 1 and severe Type 2, the key is simply missing. Understanding which failure you are dealing with determines everything about how it is managed.