Bg Symptomatologyempirical Findings

Several characteristics of BG symptoms contribute to their complexity. One of these is the lack of specificity of many of the symptoms caused by glycaemic changes7. In other words, while both hypo- and hyperglycaemia can cause numerous physical symptoms, many of these are not exclusively related to glycaemic changes and, in fact, co-occur with a number of other physiological states (e.g. hunger, fatigue, weakness, trembling, dry mouth). The list of potential symptoms that can be caused by hypo- and hyperglycaemia is quite long, because extremes in BG levels can have an impact on nearly every organ system, including a dramatic impact on the central nervous system. Table 7.1 lists the symptoms most commonly associated with hypo- and hyperglycaemia.* It is important to emphasize, however, that a given individual patient will not experience all of these symptoms. This is because BG symptomatology is highly idiosyncratic. Early studies found that no one symptom was associated with hypo- and hyperglycaemia for all patients11. Instead, the symptoms that most reliably co-vary with BG can differ greatly from patient to patient. This symptom idiosyncracy has been repeatedly demonstrated across all age groups—in children and adolescents, as well as adults with type 1 diabetes12-1 . As Table 7.1 indicates, some symptoms can also occur with both hypo- and hyperglycaemia which means that, for one patient, a symptom such as fatigue may signal low BG while, for another patient, fatigue is a sign that glucose levels are high. Several factors appear to contribute to the idiosyncracy of BG symptomatology, including individual differences in physiological responses to glucose changes (e.g. hormonal reactions), as well as psychological differences in symptom perception (e.g. attentional biases).

In addition to those sensations typically viewed as physical symptoms (e.g. pounding heart, dry mouth), Table 7.1 shows that both hypo- and hyperglycaemia can cause changes in mood, mental/motor function, and behaviour. These sequelae are also idiosyncratic in nature. For example,

*The symptoms listed in Table 7.1 represent those which have been demonstrated empirically to relate to BG levels. Empirically-related symptoms are identified using a repeated-measures procedure in which patients rate the extent to which they are experiencing symptoms on a checklist, then measure their BG and record this value. Symptom ratings and BG values can be recorded on paper checklists or entered into handheld computers. This procedure is repeated several times each day over a several-week period.

Blood Glucose Awareness Training 173

Table 7.1. Blood glucose symptoms in type 1 diabetes




Dry mouth, throat



Pounding heart

Need to urinate

Fast pulse

Stomach pain

Changes in body temperature


Heavy breathing


Slowed thinking


Difficulty concentrating

Blurred vision

Mental confusion


Slurred speech

Tingling/pain in extremities

Blurred vision





Mental confusion








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