SMBG

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SMBG

• Chien-Wen Chou MD.
• Endocrinology Metabolism Division
• Chi-Mei Medical Center
• 8 Jul 2005

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Daily Self-Monitoring

• To detect asymptomatic hypoglycemia
• To guide patient and provider behavior toward
  reaching blood glucose goals

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Introduction

• A strict glycemic control reduces the risk of the
  development of micro- and macrovascular
  complications .
• In the U.K. Prospective Diabetes Study, each 1
  reduction in HbA1c was associated with a 37
  decrease in risk for microvascular complications
  and a 21 decrease in risk for any end point or
  death related to diabetes.
• In clinical practice, a 3-monthly visit to the
  general practitioner is recommended for the
  assessment of glycemic control.
• There is now much debate on the effectiveness of
  self-monitoring of blood glucose (SMBG) as a tool
  in the self-management of diabetic patients.

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Introduction

• SMBG aims at collecting information on blood
  glucose levels at different time points during
  the day and allows for the timely identification
  of high levels.
• SMBG has proven effective for patients with type
  1 diabetes and patients with type 2 diabetes who
  are using insulin because the information about a
  patients glucose level is useful to refine and
  adjust insulin dosages, resulting in an improved
  glycemic control.

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DCCT

• A total of 1441 patients with IDDM -- 726 with no
  retinopathy at base line (the primary-prevention
  cohort) and 715 with mild retinopathy (the
  secondary-intervention cohort)
• were randomly assigned to intensive therapy
  administered either with an external insulin pump
  or by three or more daily insulin injections and
  guided by frequent blood glucose monitoring
• or to conventional therapy with one or two daily
  insulin injections.

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• Figure 1. Measurements of Glycosylated Hemoglobin
  and Blood Glucose in Patients with IDDM Receiving
  Intensive or Conventional Therapy.

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Frequency of Blood Glucose Monitoring in Relation
to Glycemic Control in Patients With Type 2
Diabetes

• Maureen I. Harris, PHD, MPH Diabetes Care
• 24979-982, 2001

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NHANES III (Sep 1988 to Oct 1994)

• 29 treated with insulins
• 65 treated with oral agents
• 80 treated with diet alone had never monitored
  or less than once per month
• Self-monitoring at least once per day 39 of
  those taking insulin
• 5-6 of those treated with oral agents or diet
  alone

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NHANES III (Sep 1988 to Oct 1994)

• Patients who tested their blood glucose increased
  with an increasing HbA1c value
• Examined by diabetes therapy category, little
  relationship between HbA1c value and the
  proportion testing at least once per day or the
  proportion testing at least once per week

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Table 1 HbA1c values and frequency of blood
glucose self-monitoring by patients with type 2
diabetes, according to diabetes treatment
The upper limit of normal for HbA1c in the assay
system is 6.1, defined as the mean 2 SDs (5.27
0.86) for the group of people with fasting
plasma glucose lt110 mg/dl and 2-h postchallenge
glucose lt140 mg/dl.
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NHANES III (Sep 1988 to Oct 1994)

• A cross-sectional study
• Medicare reimbursement the cost of blood glucose
  monitors and test strips for monitors only for
  patients with insulin
• In 1998, this policy was changes to reimburse
  patients for these items, regardless of whether
  the patient is treated with insulin
• 1997-1999, the proportion of all diabetic
  patients who self-monitored at least once per day
  was 44

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Frequency of Blood Glucose Monitoring in Relation
to Glycemic Control in Patients With Type 2
Diabetes

• Diabetes Care
• 25245-246, 2002

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ISIS Group (Oct 1996 to Sep 1999)

• gt3000 clinic visits of 228 patients with type 2
  diabetes
• Average HbA1c decreased by 0.8
• 21 of patients were regular SMBG performers
• 70 of these patients had HbA1c lt 8
• For the 42of patients who were irregular SMBG
  performers
• 37 of patients not monitoring, only 18 and 22
  respectively, had HbA1c lt 8

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Table 1 Influence of health care providers
contact on clinical effect of SMBG
HbA1c
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Self-Monitoring of Blood Glucose in Patients With
Type 2 Diabetes Who Are Not Using Insulin

• Diabetes Care
• 281510-1517, 2005

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Conclusion

• In our review, six randomized controlled trials
  could be included to evaluate the effects of SMBG
  in patients with type 2 diabetes who are not
  using insulin.
• The overall effect of SMBG was a statistically
  significant decrease of 0.39 in HbA1c compared
  with the control groups.
• This is considered clinically relevant.
• Based on the U.K. Prospective Diabetes Study, a
  decrease of 0.39 in HbA1c is expected to reduce
  risk of microvascular complications by 14

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Variability in response to SMBG

• Multiple factors impact upon an outcome such as
  A1C.
• As an example, baseline A1C values may reflect
  important clinical situations that impact design,
  particularly when disproportionately high or low.
  
• Patients with A1C close to normal may not show
  much change with either SMBG or usual care, and
  inclusion of a large number of such patients in
  studies may minimize differences between groups.
• Very poor glycemic control may also be associated
  with little benefit of SMBG.
• In type 2 diabetic patients with high A1C on
  maximal dose and number of oral agents, insulin
  therapy may be the only solution to improve
  glycemic control and SMBG would be unlikely to
  influence the outcome.

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Variability in response to SMBG

• The number of oral agents per patient was not
  clearly described in many of the six studies, or
  if reported, subjects on such a regimen were not
  always equally divided between intervention and
  control groups.
• Finally, the actual number of SMBG measurements
  performed in the course of the study or their
  relationship to meals is not always reported
• understanding effectiveness requires that
  compliance with SMBG frequency and timing also be
  documented and reported.

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SMBG Use and Frequency

• Insulin-treated patients should monitor their
  blood glucose level varies from person to person
• At least four times a day.
• Most commonly fasting, before meals, and before
  bed
• In addition, patients using insulin can benefit
  by obtaining postprandial blood glucose readings
  to help them more accurately adjust their insulin
  regimen

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SMBG Use and Frequency

• For patients with type 2 diabetes, optimal SMBG
  frequency varies depending on the pharmaceutical
  regimen and whether patients are in an adjustment
  phase or at their target for glycemic control
• If a patient is on a stable oral regimen with
  HbA1c concentration within the target range,
  infrequent SMBG monitoring is appropriate.
• In such cases, patients can use SMBG data as
  biofeedback at times of increased stress or
  changes in diet or physical activity.

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SMBG Use and Frequency

• For patients whose diabetes is out of control or
  for those having medication initiated, however,
  SMBG data can be helpful in creating or modifying
  the diabetes management regimen.
• Persistent fasting hyperglycemia, for example,
  might indicate excessive hepatic glucose output,
  and patients experiencing this problem might
  derive benefit from using metformin (Glucophage),
  which has been shown to decrease nocturnal
  hepatic glucose output.
• Additionally, patients with persistent
  postprandial hyperglycemia might derive benefit
  from taking a short-acting oral agent with meals
  to either decrease carbohydrate absorption (i.e.,
  an alpha-glucosidase inhibiter such as acarbose
  Precose or miglitol Glyset) or stimulate
  insulin secretion at the time of the meal (i.e.,
  repaglinide Prandin or nateglinide Starlix).

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SMBG Use and Frequency

• People with type 2 diabetes who use insulin
  should perform SMBG at least four times per week,
  including at least two fasting and two
  postprandial values.
• Additional measurements at bedtime and before
  meals can also be obtained.

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