In part one of resident diabetic Henry Stewart's ongoing four-part series, Insulin is Not a Cure, the author recounted collapsing from an insulin overdose and explained how, without insulin, he would starve to death.

A friend recently asked me how I was managing my diabetes—“no flare-ups?”—and I had to laugh, because diabetes usually feels like nothing but “flare-ups”. Insulin is a volatile substance. It doesn’t have “possible” side effects—its side effects are guaranteed.

At its easiest, insulin is exhausting. The way most people think of “medicine” is as a stable compound, usually in tablet form, that makes us better without making us actually feel anything—without making us conscious of how it works. An aspirin clears a headache as though by magic. Drugs intended to lower our cholesterol levels do so without providing an accompanying sensation of our arteries being scraped clear.

But insulin is not a pill diabetics must remember to take with meals that then quietly does its business: it’s a shot, like adrenalin or cocaine, with a palpable effect. You feel insulin wear off, too: sometimes in the form of mental lethargy, sometimes as weariness, sometimes as deep body aches. Some days, the best I’ll feel is in the morning, before breakfast, before that first shot.

At its worst, insulin can be fatal. That isn’t novel—it’s true of many medicines—but with insulin the possibility of overdose is so simple, so tied to the therapy. To overdose on aspirin requires deliberateness; to overdose on insulin, you need simply to misjudge a particular dosage. Not even by a lot—a single unit (roughly 1/10 of a milliliter) could make a terrible difference, as if one aspirin would clear your headache but two would end your life.

Insulin’s greatest danger is its most common side effect: hypoglycemia, or “low blood sugar”. While it’s possible, and extremely rare, for a non-diabetic to suffer mildly from this condition—usually active children who forgo a snack, or fasting alcoholics—it’s essentially a modern-day, man-made malady.

In The Discovery of Insulin, the historian Michael Bliss describes one of the Toronto researchers in the early 1920s encountering hypoglycemia in rabbits, induced by injected insulin ("the extract"), possibly for the first time in human history: "When he first began injecting the extract into normal rabbits he had noted how very hungry they became as their blood sugars fell, some of them avidly eating paper or wood shavings. As he started using more potent batches of extract, the rabbits would occasionally go into convulsive seizures. Their heads snapped back, eyeballs protruding, limbs rigid, they would violently toss themselves from side to side, then collapse into a kind of coma, lying still on their sides and breathing rapidly. The slightest stimulation, such as a shaking of the floor, would set them off again. Sometimes lying on its side the animal's limbs would move rapidly, as in running. The convulsions would recur every fifteen minutes or so until in most cases the rabbit died, rigor mortis setting in immediately."

The first time it happened to me, I was asleep, hours after drinking two glasses of red wine and eating about a pumpkin’s worth of pumpkin seeds. I awoke sweating so profusely that I worried, for a moment, that I’d pissed the bed. (An untreated diabetic’s unquenchable thirst and subsequent need to pee can often result in enuresis.) It felt like I’d been holding my breath for hours and violently came-to with a fever of 106; like my blood had stopped circulating, like my brain was pulling it all up with a force equal to that of an airplane door opened mid flight. And it still was not enough. I was thirsty. I was starving. I could hear my brain growling like a stomach. It was like coming out of hibernation, like I was alive but hadn’t eaten in months.

In a panic, I ate literally every foodstuff in the refrigerator that night—whatever leftovers from whatever dinners, whatever stray pieces of fruit, whatever salad remnants. My girlfriend woke up a few minutes after me and, on her way to the bathroom, caught me sitting alone, in the dark, at the kitchen table, eating peanut butter out of the jar with a spoon. She looked at me for a long moment, and then slipped silently through the bathroom door, later explaining she thought she’d stumbled upon some hitherto-unknown ritual of mine that was none of her business.

When I saw her, I wanted to call out, to beg her to stay with me and make sure I didn’t die. Because hypoglycemia feels like a slow descent into death. But I couldn’t find the words, nor the strength required to sound them. Instead, I began again shoveling peanut butter past my slackened jaw.

Part Three, in which Henry explains why he can't be his pancreas, as well as the dangers of walking down the street without any sugar in his blood, will appear tomorrow.