Diabetes mellitus (DM) is a heterogenous metabolic disorder characterized by the presence of hyperglycemia with carbohydrate, protein and fat metabolism disturbance which results from defects in either insulin secretion or action.
Patients with DM usually present with polyuria, polydipsia and unexplained weight loss.
Type 1 DM is caused by beta cell destruction which leads to complete insulin deficiency. It may be immune mediated or idiopathic.
Patients may present with ketoacidosis or acute onset of hyperglycemia while other patients may resemble type 2 DM or symptoms of other autoimmune disorders.
Type 2 DM is the most common form of diabetes. It is secondary to defect in insulin secretion concomitant with insulin resistance.
Majority of patients are asymptomatic. Ketoacidosis is uncommon and is usually secondary to stress (eg infection).


  • Glycemic control is essential in the management of diabetes mellitus
  • Clinical trials have proven significant reduction of microvascular complications with improved glucose control
  • Patient self-monitoring of blood glucose or interstitial glucose monitoring and HbA1c are used for assessing the effectiveness on glycemic control

Self-monitoring of Blood Glucose (SMBG)

  • Permits patients to evaluate their response to therapy and check whether glucose targets are being achieved
    • May be used as a guide to the success of therapy for patients using less insulin injections, oral antidiabetic agents or medical nutrition therapy alone
  • Results may help prevent hypoglycemia and adjust medications (especially prandial insulin doses), medical nutrition therapy, and physical activity
  • Postprandial self-monitoring of blood glucose may be performed to achieve postprandial glucose targets
  • Frequency and timing are dependent on the patient’s glucose status, needs and goals and mode of treatment
    • Should be done by patients on multiple-dose insulin or insulin pump therapy at least prior to meals and snacks, occasionally postprandially, at bedtime, prior to exercise, when low blood glucose is suspected, after treating low blood glucose until normoglycemic, and prior to critical tasks such as driving
    • Important for patients on insulin to monitor and prevent asymptomatic hypo- or hyperglycemia
    • For patients with type 2 diabetes mellitus on oral antidiabetic therapy, frequency and timing is unclear

Continuous Glucose Monitoring (CGM)

  • Helpful in identifying glucose variations in patients with poorly controlled diabetes
  • Valuable tool when used in conjunction with intensive insulin regimens to lower HbA1c in patients with type 1 diabetes mellitus
  • May be a supplemental tool to self-monitoring of blood glucose in patients with frequent hypoglycemia and/or those with hypoglycemia unawareness
  • Have alarms for hypo- or hyperglycemic excursions
  • Results are accurate, similar to self-monitoring of blood glucose
Glycosylated Hemoglobin A1c (HbA1c)
  • Formed by a non-enzymatic glycation of hemoglobin
  • Reflects average glycemia over 3 months and has strong predictive value for diabetes mellitus complications
  • Recommended to be done at initial assessment and then as part of continuing care
    • Every 3 months measurement may determine whether patient’s glucose targets have been achieved and maintained
  • Frequency should be based on individual’s clinical situation and treatment regimen used, and physician’s judgment
  • Should be performed at least 2 times per year in patients who are meeting treatment goals and have stable glucose control
  • Should be done 4 times per year in patients whose therapy has changed or those not reaching glycemic goals
  • Results in increased intensification of therapy and improvement in glycemic control when used as a point-of-care testing
  • May check accuracy of the patient’s meter or the reported results of self-monitoring of blood glucose, and sufficiency of the timing or frequency of self-monitoring of blood glucose
  • Does not measure glycemic variability or hypoglycemia
    • Glycemic control is best evaluated by self-monitoring of blood glucose plus HbA1c in patients with type 1 diabetes mellitus and type 2 diabetes mellitus with severe insulin deficiency
  • May be affected by conditions that affect erythrocyte turnover (eg hemolysis, blood loss, blood transfusion or hemoglobinopathy) as well as renal impairment

Glycemic Goals

  • Individualized based on the duration of diabetes mellitus, age/life expectancy, comorbid conditions, cardiovascular disease or advanced microvascular complications, hypoglycemia unawareness and individual patient preference
  • HbA1c <7% have been shown to reduce microvascular and neuropathic complications of diabetes mellitus, and is associated with long-term reduction in macrovascular disease if implemented right after diagnosis has been made
  • HbA1c ≤6.5% may be advised in patients with diabetes mellitus of short duration, with long life expectancy, and no significant cardiovascular disease; given that this can be achieved without causing significant hypoglycemia
  • HbA1c <8% may be allowed in patients with history of severe hypoglycemia, limited life expectancy, advanced micro- or macrovascular complications, extensive comorbid conditions, and to those with long-standing diabetes mellitus who did not reach their target glucose level despite treatment and appropriate monitoring
  • Preprandial capillary plasma glucose goal: 3.9-7.2 mmol/L (70-130 mg/dL)
  • Peak postprandial capillary plasma glucose goal: <10 mmol/L (<180 mg/dL)
    • Monitoring postprandial glucose 1-2 hrs after the start of a meal
    • Recommended in patients with acceptable fasting glucose but have HbA1c value above target
    • Studies have shown that Insulin regimens targeting postprandial glucose has no cardiovascular disease benefit as compared to those targeting preprandial glucose
  • Severe or frequent hypoglycemia is an absolute indication for adjusting treatment regimen which includes higher glycemic goals
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