Our family celebrates birthdays with food.

When my turn came last month, we had a blowout at Zahav in Center City, complete with specialty bourbon cocktails and the fixed-price menu, which included Israeli salads of sugary beets and carrots, hummus, pita bread, roasted lamb, and three different desserts for the table.

In my rush to arrive on time, I had accidentally left my type 2 diabetes medications behind. As a regularly well-controlled person with diabetes, I didn't let that worry me too much. Tossing my normal caution and strict carbohydrate-counting aside, I enjoyed every sip and bite.

It was my birthday, I told myself.

By the time I reached home after the huge meal, I was exhausted, thirsty, and oddly hungry. I downed a sugarless chocolate bar and some nuts with two Diet Cokes, and then, still ravenous, went whole hog on a small carton of chocolate Ben & Jerry's ice cream buried in the back of the freezer.

In the middle of the night, I awoke with a dry mouth and an urge to urinate. I was soaked in sweat. The next morning, I was fatigued from lack of sleep, and my sugar reading, normally around 100, had peaked at an unacceptable 198.

I felt lousy.

Once again, I learned the tough lesson: I may temporarily forget diabetes, but diabetes never forgets me. Even on my birthday, eating a huge meal with excessive carbohydrates wreaks havoc on my metabolic system and blood glucose.

Yet everyone else at the table ate just as I did and felt fine. What caused my body to react so differently?

Here's the inside story: After you eat any type of food that contains carbohydrates - from doughnuts to baked potatoes to orange juice - the carbs are broken up into glucose molecules, the sugars that provide fuel for the body, particularly the brain.

Using this fuel requires the hormone insulin, produced in the pancreas. Its job is to regulate the amount of sugar going in and out of the body. Insulin allows sugar molecules to enter cells so they can produce energy. Another hormone, glucagon, can raise sugars if they fall too low.

Striking the right balance between high and low sugars is called glucose homeostasis. In people without diabetes (including my birthday dinner companions), this process happens automatically.

But when you have diabetes, this equilibrium is harder to achieve. In type 1 diabetes, an autoimmune disease, the body produces no insulin, so patients need to take injections of insulin before meals. In type 2, people develop insulin resistance, which means insulin cannot "unlock" the cells to get sugar molecules inside. Type 2 diabetics can also produce less insulin over time.

"In insulin resistance, glucose molecules line up at cells like dinner guests who can't get in the door," said Katie Gill, a registered dietitian at Thomas Jefferson University Hospitals.

Unable to enter the cells, some of the excess glucose molecules are metabolized into fat; others float in the bloodstream, raising blood-glucose levels and generally causing havoc. My symptoms - fatigue, a need to urinate as my kidneys tried to excrete the extra sugars, and a dry mouth - are the result. To regain energy, some people reach for high-carbohydrate snacks - like my chocolate Ben & Jerry's - that only make blood-glucose sugars climb higher.

Left unchecked, uncontrolled blood sugars can cause devastating complications, including kidney disease, nerve damage, and problems with the eyes and heart.

"People without diabetes are lucky because their body is kind of on autopilot," said Mitchell Lazar, director of the Institute for Diabetes, Obesity, and Metabolism at Penn Medicine. "But a diabetic can't rely on their own body making those decisions, and they have to be part of the decision-making process."

Which isn't always easy, even for someone like me who has done well for years on a careful regimen featuring a carb-limited diet, medication, and exercise.

The next day, I tried not to obsess over the number on the glucose monitor or on the scale. Instead, I took my morning medications, returned to my low-carbohydrate diet, drank plenty of fluids, and did my regular hour of exercise.

Soon, my blood sugar receded to a normal level.

"When it comes to diabetes, you are part of the disease," said Lazar. "You can't just take a pill and count on it to take care of things. The treatment is not just a medicine; it's your lifestyle. And you control that."

It's a good thing birthdays come only once a year.