Based on my experience, I recommend the following after-meal goals for the following groups. These numbers are generally achievable, lead to a decent A1C level, and do not interfere with daily quality of life:
- Adults who take mealtime insulin: below 180 mg/dl
- Adolescents (12–18): below 200 mg/dl
- School-age children (6–11): below 225 mg/dl
- Preschool-age and toddlers (5 or younger): below 250 mg/dl
- People with Type 2 diabetes who do not take mealtime insulin: below 140 mg/dl
After-meal readings that are consistently above these levels should be addressed by you and your health-care team (see strategies in the sections below).
Besides monitoring with a conventional blood glucose meter, a few other options exist for detecting post-meal spikes. Continuous glucose monitoring (CGM) systems provide glucose readings every couple of minutes and provide trend graphs that make it easy to see exactly what is happening after meals and at other times of the day. (See an example of a trend graph here.) Medtronic and DexCom both make CGM devices.
Individuals can purchase a CGM for long-term or ongoing use, or, alternatively, some specialized diabetes centers offer them on a temporary or loaner basis. (Feel free to contact my office for a loaner if your providers do not offer them.) CGM systems include a tiny sensor filament that is inserted just below the skin, a small radio transmitter attached to the sensor, and a handheld receiver that displays your data. The systems are all uploadable to a computer for analysis of the information.
Another way to assess after-meal blood glucose control is with a blood test trade-named GlycoMark. GlycoMark measures the level of a specific type of sugar (1,5-anhydroglucitol, or 1,5-AG) that becomes depleted whenever the kidneys are spilling glucose into the urine; this typically occurs when blood glucose exceeds approximately 180 mg/dl. The test result reflects blood glucose levels over the prior one to two weeks. Ask your diabetes doctor if this test is available near you.
Medical approaches to spike control
A common approach to lowering after-meal blood glucose spikes is to take more insulin. But unless blood glucose levels remain high for three to six hours after eating, taking more insulin is not going to solve the problem. In fact, increasing mealtime insulin will most likely result in low blood glucose before the next meal.
Here are some strategies that may work better:
Choose the right insulin (or other medicine). The right insulin or medicine program can make or break your ability to control after-meal spikes. In general, insulins and other medicines that work quickly and for a short time will work better than those that work slowly over a prolonged period.
For instance, rapid-acting insulin analogs (brand names Humalog, NovoLog, and Apidra), which start working 10–15 minutes after injection and peak in about an hour, cover the after-meal blood glucose rises much better than Regular insulin, which takes 30 minutes to begin working and 2–3 hours to peak. If you use a morning injection of NPH insulin to “cover” the carbohydrate eaten in the middle of the day, your blood glucose level after lunch and after any daytime snacks is likely to be very high. This is also the case if you take a premixed insulin (75/25, 70/30, or 50/50) twice daily. For fewer spikes, consider taking a rapid-acting insulin before each meal or snack and using a long-acting “basal” insulin such as Lantus or Levemir for coverage between meals.
If you use oral diabetes medicines, your choice of pill can also affect your after-meal blood glucose control. Sulfonylureas (glyburide, glipizide, and glimepiride) stimulate the pancreas to secrete a little extra insulin throughout the day, without regard to meals. Because these medicines fail to concentrate the insulin secretion at times when it is needed most, after-meal blood glucose levels can run very high. However, there are two other oral medicines, repaglinide (Prandin) and nateglinide (Starlix), which also stimulate the pancreas to release more insulin but do so in a much faster and shorter manner. When taken at mealtimes, these drugs may produce better after-meal control than a sulfonylurea.