Diabetes Treatment: How Much Insulin Do You Need?

If you have type 2 diabetes and your doctor thinks it might be a good time to start insulin therapy, there are two important factors to consider: How much insulin do you need to take? When do you need to take it? 

And both are very personal.

"You can't paint everyone with type 2 diabetes with the same brush," says Mark Feinglos, M.D., division chief of endocrinology, metabolism,\ and nutrition at the Duke University School of Medicine, in Durham, N.C. "You need to tailor the regimen to an individual's needs."

A person with type 2 diabetes might start off on half a unit of insulin per kilogram of body weight per day, especially if there is not much known about the nature of his or her diabetes. Still, it is not unusual to need more like one unit, says Dr. Feinglos. (One unit per kilogram would be 68 units per day for someone who weighs 150 pounds, which is about 68 kilograms.)

A lot depends on your specific health situation. People with type 2 diabetes suffer from insulin resistance, a situation in which the body loses its ability to use the hormone properly. Early in the course of the disease, the insulin-producing cells of the pancreas respond to insulin resistance by churning out even more of the hormone. Overtime, though, insulin production declines.

Taking insulin can help you overcome the body's insulin resistance, though many factors can affect your dosage. If your body is still sensitive to insulin but the pancreas is no longer making much insulin, for example, Dr. Feinglos says that you would require less insulin than someone who is really resistant to insulin.

"But the most important issue is not necessarily how much you need to take," he adds. "Rather, it's the timing of what you to take. Timing is everything."

One Shot A Day Or More?

If you wake up with high blood sugar in the morning, it's very likely that you will need at least a once-a-day injection combined with oral drugs, says Dr. Feinglos. Oral medication can lower your insulin resistance, and a long-acting, once-a-day insulin shot (usually taken at bedtime) can mimic the low level of insulin made by the pancreas. (And the shots may not be how you picture them -- painful and complicated. You can use pen-like injectors that have short, thin needles and that allow you to dial the amount of insulin you require, rather than draw it up from a vial using a syringe.)

If your blood sugar tends to spike after meals despite using medication and watching what you eat, you may have to take a dose of rapid-action insulin before every meal.

"There's controversy over how much better you can really do with additional shots," says John Buse, M.D., Ph.D., director of the Diabetes Care Center at the University of North Carolina School of Medicine, in Chapel Hill. "I don't see much improvement in overall glucose control in many patients with the rapid-acting insulin taken at meals. And it does promote weight gain and low blood sugar. Is the burden worth the benefit?"

Either way, a once-a-day long-acting formulation is usually the best way to start, according to Dr. Buse. A standard initial dose might be 10 units. The dosage is then increased until blood sugar levels are lowered into the normal range.

"If a person still has substantial insulin secretion left in their pancreas, one shot a day is probably more than enough to top it off," agrees Robert Rizza, M.D., professor of medicine and executive dean of research at the Mayo Clinic, in Rochester, Minn. "But if you're really running out of insulin and can't store it between meals, then you may need to take both the long and short-acting injections."

Taking Insulin With Meals

If you do end up taking insulin at meals, the doctors agree that it is particularly important to match food intake with insulin, while also accounting for physical activity. (Exercise naturally lowers blood sugar, so if you're working out, you may need to take that into account.)

"Some people recommend matching insulin to carbohydrate counts," says Dr. Buse. "Others suggest eating a set serving of carbohydrates at each meal for a particular dose of insulin."

Even more crucial, according to Dr. Feinglos, is moderating food intake before insulin is ever initiated. "If you're not controlling the calories first, and just start giving insulin," he warns, "then all a patient is going to do is gain weight and get more insulin resistant and end up needing larger doses of insulin."

It Can Be A Vicious Cycle

"The relationship between food and exercise with medicine is so critical in diabetes," he adds. "If you just keep pouring medicine into the problem, it doesn't really solve it."

Nevertheless, a patient may do everything right -- eat well, work out and routinely take his or her medicine -- but still require more insulin over time due to the progressive nature of the disease. Adjustments can come through higher doses, increased frequency of injections, or both.

On a positive note, with improved diet and exercise, some patients are actually able to reduce their intake, even to the point of discontinuing insulin injections altogether.

"There are multiple ways to get to the same point," says Dr. Rizza. "The bottom line is to keep blood sugar normal."