Daytime NPH

Advantages

• Physicians most familiar with this program

• Can use insulin premixes for convenience and accuracy of insulin proportions

Disadvantages

• No flexibility for dietary or exercise variations

• Morning NPH predisposes to late-morning and early-afternoon hypoglycemia requiring between-meal snacks

• Pre-supper NPH predisposes to middle-of-the-night hypoglycemia and/or inadequate control of fasting blood glucose level

Program

Figure 3 shows how daytime NPH regimens are generally used—the two-shot program in Figure 3A is NPH with Regular or a rapid-acting analog before breakfast and supper (this is given as premixes in some patients), and the three-shot program in Figure 3B is NPH and Regular or a rapid-acting analog before breakfast, Regular or the rapid-acting analog at dinner, and NPH at bedtime (by 11 p.m. even if staying up past that time).

Overview

No discussion of insulin therapy would be complete without including daytime NPH, the most popular insulin regimen in the United States. However, experts argue against its use in type 1 diabetes, because inherent limitations make it difficult, if not impossible, to obtain the glycemia goals in Table 2 without unacceptable hypoglycemia. Indeed, the DCCT study, which was begun in 1985 and planned a few years earlier, allowed only an Ultralente regimen or insulin pump in the intensively treated group and instead assigned NPH to conventional therapy (1). Thus, NPH-based regimens are generally appropriate only for patients who are not candidates for intensive glycemic control.

The major limitation of this regimen is having to use NPH in the morning to provide lunchtime insulin coverage through its "slow on, slow off' action. This leads to hyperinsulinemia from the midmorning to the late afternoon, which makes patients prone to hypoglycemia. Even with midmorning and midafternoon snacks, many patients still experience late-morning "shakes" or "jitters." To avoid this, they generally take insufficient NPH to cover the post-lunch glycemia, which protects against hypoglycemia but also results in hyperglycemia that continues through much of the afternoon. Further, wanting to alter the timing or type of lunch poses an insurmountable problem with this regimen. Exercise is also problematic because of the prolonged hyperinsulinemic effect of NPH, which promotes peri- or post-exercise hypoglycemia. Thus, patients are locked into a regimented lifestyle, with virtually no flexibility for variations in diet or exercise if they are to avoid hypoglycemia. Some patients expand the flexibility of this

Figure 3 Conventional NPH insulin regimens showing the number of injections and time of administration relative to meals (B = breakfast; L = lunch; S = supper) and bedtime <HS). (Top) twice-daily NPH insulin and rapid-acting analog. (Bottom) the three-shot regimen, which splits the evening insulin into rapid-acting analog at supper and NPH at bedtime. The shaded area depicts the normal 24-hour pattern of insulin secretion from Figure 1. Insulin levels from each program are shown as broken or solid lines based on the pharmacokinetics of the different insulin preparations. Convergence of the perimeter of the shaded area and the insulin lines indicates correct insulin activity. Non-convergence is too little, or too much, insulin effect.

Figure 3 Conventional NPH insulin regimens showing the number of injections and time of administration relative to meals (B = breakfast; L = lunch; S = supper) and bedtime <HS). (Top) twice-daily NPH insulin and rapid-acting analog. (Bottom) the three-shot regimen, which splits the evening insulin into rapid-acting analog at supper and NPH at bedtime. The shaded area depicts the normal 24-hour pattern of insulin secretion from Figure 1. Insulin levels from each program are shown as broken or solid lines based on the pharmacokinetics of the different insulin preparations. Convergence of the perimeter of the shaded area and the insulin lines indicates correct insulin activity. Non-convergence is too little, or too much, insulin effect.

(Figure 3A), in most people, NPH is not a 12-hour insulin so fasting hyperglycemia occurs, and increasing the suppertime NPH dose to try to optimize the fasting blood glucose level often leads to middle-of-the-night hypoglycemia. An exception is when the metabolism of insulin is slowed so the NPH activity persists until the next morning. This is seen in elderly patients because of their reduced glomerular filtration rate, which explains why twice-a-day premixed insulins are successful in some of those patients. Impaired renal function also slows insulin metabolism. Otherwise, it is recommended that the nighttime insulin be given in two injections: the short-acting insulin at supper and the NPH at bedtime (Figure 3B). Some practitioners are confused about the risk of nocturnal hypoglycemia with this three-shot program. If the NPH is taken at 10:00 p.m., and it has a 68-hour peak, they reason that the peak will be at 4-6 a.m. and cause prewaking hypoglycemia. Remember that insulin requirements begin to rise at 3:00 a.m. because of the dawn phenomenon; NPH peaking before we awake is in fact advantageous for control of the fasting blood glucose level.

How do you do it?

1. Calculate the 24-hour insulin need as described in Table 4.

2. Give two-thirds of the 24-hour dosage in the morning, with two-thirds as NPH, the other one-third as Regular or a rapid-acting analog.

3. Give the remaining one-third of the 24-hour dosage in the p.m., with one-half as NPH and the other half as Regular or the rapid-acting analog. it is given as a single injection at supper in the two-shot program; in the three-shot program it is divided, with the Regular or rapid-acting analog given at supper and the NPH at bedtime (before 11 p.m. even if staying up later).

4. Adjust these starting dosages if the patient has unusual eating, exercise, or work habits,

5. Perform daily fasting, pre-meal or 2-hour postmeal, and bedtime SBGM along with weekly middle-of-the-night SBGM.

6. Example: 70-kg male who is moderately physically active. Total daily insulin dose is 70 kg X 0.4 units/kg = 28 units. Total a.m. insulin: 28 X 67% = 18 units, a.m. NPH: 18 X 67% = 12 units, a.m. Regular or rapid-acting analog: 18 X 33% = 6 units. Total p.m. insulin: 28 X 33% = 9 units, p.m. NPH: 9 X 50% = 5 units, p.m. Regular or rapid-acting analog: 9 X 50% = 5 units. Final (two shots): 12 units NPH and 6 units Regular or rapid-acting analog at breakfast, and 5 units NPH and 5 units Regular or a rapid-acting analog at dinner. Final (three shots): 12 units NPH and 6 units Regular or rapid-acting analog at breakfast, 5 units Regular or rapid-acting analog at dinner, 5 units NPH at bedtime. Adjust insulin doses as needed based on the SBGM values to attain the predefined glycemia goals.

Was this article helpful?

0 0
Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

Get My Free Ebook


Post a comment