QUESTION
What Percentage of patients with type 2 diabetes regularly
check postpandial blood glucose (blood glucose 2 hrs after eating)?
Answer:
1. 25%
2. 50%
3. Less then 10%
4. Greater than 50%
In a recent Diabetes In Control Survey, where we asked over 500 patients
with diabetes coming into pharmacies for medication for diabetes,
“Do you check your blood glucose 2 hours after you eat”?
Less then 10% responded that they were checking their postprandial
blood glucose. Less then 5% are checking it regularly.
90% of the patients were being treated by their family practioners
and were told to check their fasting blood glucose.
Most physicians specializing in the treatment of diabetes have their
patients checking their postprandial blood glucose. But only 10% of
patients with diabetes see a physician who specializes in diabetes.
Why test blood sugars more then just fasting?
First, the purpose of glucose testing is to allow patients with diabetes
to achieve optimal glycemic control while avoiding hypoglycemia. As
many patients with diabetes tend to have relatively high fasting glucose
levels in the morning, a phenomenon referred to as the "dawn
phenomenon,"[1] restricting glucose measurements to this time
decreases the likelihood of detecting low glucose levels, which typically
occur in the late afternoon and, more dangerously, during the night.
Furthermore, hypoglycemia may occur at different times in different
patients. Thus, a strategy of testing glucose at various times during
the day is more likely to detect low glucose levels and hence decrease
the likelihood of hypoglycemia.
Second, many glucose-lowering agents, such as metformin, the thiazolidinediones,
perhaps the sulfonylureas, and the intermediate- and long-acting insulins
given at night, show their greatest effect in the fasting period.
Monitoring only fasting glucose levels might lead to the mistaken
belief that glycemia is under control, while in actuality there is
suboptimal glucose control during the day requiring additional efforts
at treatment. Both nocturnal hypoglycemia and fasting hyperglycemia
are commonly found in patients with type 1 diabetes,[2] and have been
frequently documented with new continuous interstitial glucose-monitoring
devices.[3]
The dissociation between fasting and daytime glycemia appears to explain
the failure of conventionally treated type 2 patients in the United
Kingdom Prospective Diabetes Study (UKPDS) to achieve stable control
of HbA1c during the 10-year study, in contrast to the relatively stable
fasting glucose achieved in the insulin intervention group
There is another question to be addressed, however, which is whether
postprandial glucose measurement should be performed in addition to
preprandial measurement, so that one might consider asking the patient
with diabetes to test the blood glucose before and 90-120 minutes
after each meal, at bedtime, and during the night, for a total of
8 potential testing times. There is a great deal of evidence that
the postchallenge glucose is more sensitive than fasting glucose in
the diagnosis of diabetes and in the prediction of macrovascular risk
in large populations.[4]
There is also evidence that postprandial glucose shows a stronger
correlation with HbA1c than does fasting glucose.[5] During pregnancy,
regular postprandial monitoring is certainly accepted, supported by
evidence that patients using postprandial glucose goals have improved
fetal outcomes.[6] We do not yet have evidence that using postprandial
glucose as a therapeutic target particularly benefits other patients
with diabetes.
However, various therapeutic agents specifically target postprandial
glucose. These are the alpha-glucosidase inhibitors acarbose and miglitol,
the rapidly acting insulin secretagogues repaglinide and nateglinide,
and the short-acting insulin analogues lispro and aspart, as well
as the inhaled and oral insulin preparations now being developed.
Future studies with these agents using continuous glucose monitoring
technologies will greatly increase our ability to understand the relative
benefits of pre- and postprandial glucose as therapeutic targets and
will allow a more complete answer to the question of whether patients
should routinely monitor postprandial blood glucose. At present, it
seems that monitoring postprandial glucose is logical for patients
undergoing treatment with these agents or for whom such treatment
is being considered.
Another reason to check after meals, is that it is part of the education
process. Knowing how certain foods can raise your glucose levels,
will prevent them from repeating the same mistake.
For some patients with type 2 diabetes it may not usually be appropriate
to recommend extremely frequent glucose testing, for a number of reasons
including cost. But you might suggest that each day a different meal
be "bracketed" with pre- and postprandial glucose tests,
so that over the course of a week two 6-point day-profiles can be
generated. Such an approach can be used to adjust doses of each meal's
medication, with many patients requiring smaller doses before lunch
and larger doses before dinner, particularly with repaglinide and
rapidly absorbed insulin preparations.
References
1. Bolli GB, Gerich JE. The "dawn phenomenon"--a common
occurrence in both non-insulin-dependent and insulin-dependent diabetes
mellitus. N Engl J Med. 1984;310:746-750.
2. Holl RW, Grabert M, Schwab O, et al. Factors related to the prevalence
of nocturnal hypoglycemia in hospitalized children and adolescents
with type 1 diabetes mellitus: Analysis in 2659 subjects from 62 centres.
Diabetes. 2001;50(suppl 2):A67.
3. Gibson LC, Halvorson MJ, Carpenter S, Kaufman FR. Short-term use
of the MiniMed Continuous Monitoring System to determine patterns
of glycemia in pediatric patients with type 1 DM. Diabetes. 2000;49(suppl
1):A108.
4. The DECODE Study Group. Glucose tolerance and mortality: comparison
of WHO and American Diabetes Association diagnostic criteria. The
DECODE study group. European Diabetes Epidemiology Group. Diabetes
Epidemiology: Collaborative analysis Of Diagnostic criteria in Europe.
Lancet. 1999;354:617-621.
5. Avignon A, Radauceanu A, Monnier L. Nonfasting plasma glucose is
a better marker of diabetic control than fasting plasma glucose in
type 2 diabetes. Diabetes Care. 1997;20:1822-1826.
6. de Veciana M, Major CA, Morgan MA, et al. Postprandial versus preprandial
blood glucose monitoring in women with gestational diabetes mellitus
requiring insulin therapy. N Engl J Med. 1995;333:1237-1241.
7. DIC pharmacy survey: 12 pharmacies participated over 90 days. 500
patients were asked if they checked their blood glucose 2 hours after
eating. Bedtime monitoring was considered a negative response. June
2003
