How has psycho-behavioural research advanced our understanding of hypoglycaemia in type 1 diabetes?

Almost 100 years since the discovery of insulin, hypoglycaemia remains a barrier for people with type 1 diabetes to achieve and maintain blood glucose at levels which prevent long-term diabetes-related complications. Although hypoglycaemia is primarily attributable to the limitations of current treatment and defective hormonal counter-regulation in type 1 diabetes, the central role of psycho-behavioural factors in preventing, recognizing and treating hypoglycaemia has been acknowledged since the early 1980s. Over the past 25 years, as documented in the present review, there has been a substantial increase in psycho-behavioural research focused on understanding the experience and impact of hypoglycaemia. The significant contributions have been in understanding the impact of hypoglycaemia on a person's emotional well-being and aspects of life (e.g. sleep, driving, work/social life), identifying modifiable psychological and behavioural risk factors, as well as in developing psycho-behavioural interventions to prevent and better manage (severe) hypoglycaemia. The impact of hypoglycaemia on family members has also been confirmed. Structured diabetes education programmes and psycho-behavioural interventions with a focus on hypoglycaemia have both been shown to be effective in addressing problematic hypoglycaemia. However, the findings have also revealed the complexity of the problem and the need for a personalized approach, taking into account the individual's knowledge of, and emotional/behavioural reactions to hypoglycaemia. Evidence is emerging that people with persistent and recurrent severe hypoglycaemia, characterized by deeply entrenched cognitions and lack of concern around hypoglycaemia, can benefit from tailored cognitive behavioural therapy.

An empirically derived short form of the Hypoglycaemia Fear Survey II.

AIMS: To develop an empirically derived short version of the Hypoglycaemia Fear Survey II that still accurately measures fear of hypoglycaemia. METHODS: Item response theory methods were used to generate an 11-item version of the Hypoglycaemia Fear Survey from a sample of 487 people with Type 1 or Type 2 diabetes mellitus. Subsequently, this scale was tested on a sample of 2718 people with Type 1 or insulin-treated Type 2 diabetes taking part in DIALOG, a large observational prospective study of hypoglycaemia in France. RESULTS: The short form of the Hypoglycaemia Fear Survey II matched the factor structure of the long form for respondents with both Type 1 and Type 2 diabetes, while maintaining adequate internal reliability on the total scale and all three subscales. The two forms were highly correlated on both the total scale and each subscale (Pearson's R > 0.89). CONCLUSIONS: The short form of the Hypoglycaemia Fear Survey II is an important first step in more efficiently measuring fear of hypoglycaemia. Future prospective studies are needed for further validity testing and exploring the survey's applicability to different populations.

Hypoglycaemic episodes in patients with type 2 diabetes--risk factors and associations with patient-reported outcomes: The PANORAMA Study.

AIM: To explore the frequency of hypoglycaemic episodes, their risk factors, and associations with patient-reported outcomes in patients with type 2 diabetes enrolled in the PANORAMA cross-sectional study. METHODS: Five thousand seven hundred and eighty-three patients aged ≥ 40 years with type 2 diabetes duration ≥ 1 year were recruited in nine European countries. Patients reported severe and non-severe hypoglycaemic episodes during the past year at a single study visit. Patient-reported outcomes were measured by the Audit of Diabetes-Dependent Quality of Life, Diabetes Treatment Satisfaction Questionnaires, Hypoglycaemia Fear Survey-II, and EQ-5D Visual Analog Scale. RESULTS: During the previous year, 4.4% of the patients experienced ≥ 1 severe hypoglycaemic episode; among those without severe hypoglycaemia, 15.7% experienced ≥ 1 non-severe episode. Patients experiencing any hypoglycaemic episode reported a greater negative impact of diabetes on quality of life, greater fear of hypoglycaemia, less treatment satisfaction and worse health status than those with no episodes. In multivariate analyses hypoglycaemia was significantly associated with longer diabetes duration; presence of microvascular and, to a lesser extent, macrovascular complications; treatment with insulin, glinides or sulfonylureas; and use of self-monitoring blood glucose. CONCLUSION: In patients with type 2 diabetes, severe hypoglycaemic episodes were not uncommon and one in five experienced some form of hypoglycaemia during the previous year. Hypoglycaemia was associated with more negative patient-reported outcomes. The risk of hypoglycaemia increased with diabetes duration, presence of diabetes-related complications, use of self-monitoring blood glucose, insulin secretagogues, and insulin treatment.

Examining the Behaviour subscale of the Hypoglycaemia Fear Survey: an international study.

AIMS: The Hypoglycemia Fear Survey (HFS)-II Behaviour and Worry subscales were developed to measure behaviours and anxiety related to hypoglycaemia in diabetes. However, previous studies found lower reliability in the HFS Behaviour subscale and inconsistent relationships with glucose control. The purpose of this study was to conduct extensive analyses of the internal structure of the HFS Behaviour subscale's internal structure and its relationships with diabetes outcomes, including HbA1c and episodes of severe hypoglycaemia. METHODS: HFS-II survey data from 1460 adults with Type 1 diabetes were collected from five countries. This aggregated sample underwent exploratory factor analysis and item analysis to determine the internal structure of the survey and subscales. RESULTS: A three-factor solution showed the best fit for the HFS, with two subscales emerging from the HFS Behaviour representing tendencies towards (1) maintenance of high blood glucose and (2) avoidance of hypoglycaemic risks by other behaviours, and a third single HFS Worry subscale. Subscale item analysis showed excellent fit, separation and good point-measure correlations. All subscales demonstrated acceptable (0.75) to excellent (0.94) internal reliability. HbA(1c) correlated with Maintain High Blood Glucose subscale scores, r = 0.14, P < 0.001, and severe hypoglycaemia frequency correlated with all subscales. CONCLUSIONS: The HFS Worry subscale measures one construct of anxiety about various aspects of hypoglycaemia. In contrast, the HFS Behaviour subscale appears to measure two distinct aspects of behavioural avoidance to prevent hypoglycaemia, actions which maintain high blood glucose and other behaviours to avoid hypoglycaemic risk. These results demonstrate the clinical importance of the HFS Behaviour subscales and their differential relationships with measures of diabetes outcome such as HbA1c .

Driving mishaps and hypoglycaemia: risk and prevention.

Driving is a complex, multi-task activity that can be affected by cognitive impairment resulting from episodes of severe hypoglycaemia. Intensive insulin therapy increases the likelihood of severe hypoglycaemia but there have been few studies examining effects on driving skills. A survey carried out recently indicated that patients with type 1 diabetes had twice the incidence of driving accidents than their non-diabetic spouses or patients with type 2 diabetes. The motor accidents were associated with more frequent low blood glucose while driving and less frequent self-monitoring. In driving simulation tests it was found that driving has an intrinsic metabolic demand that can contribute to hypoglycaemia. Driving performance began to deteriorate at around 3.6 mmol/l but drivers frequently did not recognise and failed to treat the hypoglycaemia. Those who did self-treat had more driving relevant symptoms and less neuroglycopenia quantified by EEG alpha-theta differences. Patients should be recommended not to begin driving if blood glucose is below 4.5 mmol/l and should not continue to drive if they suspect that blood glucose has fallen below 4 mmol/l while driving. If hypoglycaemia is suspected patients should immediately pull off the road, measure blood glucose if possible, treat themselves as necessary and not resume driving until glucose and cognitive-motor function return to normal. The problems of driving and hypoglycaemia should be discussed with patients with diabetes and behavioural interventions instigated. To this end, Blood Glucose Awareness Training (BGAT) and Hypoglycaemia Anticipation, Awareness and Treatment Training (HAATT) have been developed and shown to markedly reduce incidence of driving mishaps.

Self-treatment of hypoglycemia while driving.

OBJECTIVE: While it is clear that progressive diabetic hypoglycemia leads to neuroglycopenia, which impairs driving, it is not clear what contributes to patients' detection and subsequent self-correction of hypoglycemia/driving impairments. Drivers with Type 1 Diabetes Mellitus (T1DM) who did and did not engage in self-treatment during experimental hypoglycemia driving are compared physiologically and psychologically. METHOD: 38 drivers with T1DM drove a sophisticated driving simulator during euglycemia and progressive hypoglycemia. Subjects were continually monitored for driving performance, EEG activity and whether they self-treated with a glucose drink. Every 5 min measures were taken of blood glucose (BG) and epinephrine levels, perceived neurogenic and neuroglycopenic symptoms and driving ability. For the four weeks prior to this hospital study, subjects participated in a field study. Using a hand-held computer just prior to routine self-measurements of BG, subjects rated neurogenic and neuroglycopenic symptoms and made judgements about BG level and ability to drive as they did in the hospital. RESULTS: Drivers who did and did not self-treat did not differ in terms of their pre-hospital exposure to hypoglycemia, their depth and rate of BG fall during experimental testing, or their epinephrine response to hypoglycemia. Subjects who self-treated detected more neurogenic and neuroglycopenic symptoms than those who did not self-treat. They also experienced less EEG defined neuroglycopenia during the progressive hypoglycemic drive as compared to those who did not self-treat. Perceived need to self-treat and EEG parameters correctly classified 88% of those who did treat from those who did not self-treat. Further, subjects who self-treated were more aware of hypoglycemia and when not to drive while hypoglycemic in the field study. CONCLUSION: There is a narrow window between a patient's detection of hypoglycemic symptoms and the need to self-treat, and neuroglycopenia, which impairs self-treatment. Consequently, drivers with T1DM should be vigilant for signs of hypoglycemia and driving impairment (e.g. trembling, uncoordination, visual difficulties) and encouraged to treat themselves immediately when they suspect hypoglycemia while driving.

Blood glucose awareness training (BGAT-2): long-term benefits.

OBJECTIVE: Blood glucose awareness training (BGAT) has been shown to improve awareness of blood glucose (BG) fluctuations among adults with type 1 diabetes. This study investigates the long-term (12-month) benefits of BGAT-2. RESEARCH DESIGN AND METHODS: A total of 73 adults with type 1 diabetes participated in a 6-month repeated baseline design with a 12-month follow-up. At 6 months and 1 month before BGAT-2 and at 1,6, and 12 months after BGAT-2, subjects used a handheld computer for 50 trials and completed psychological tests. Throughout assessment, subjects completed diaries, recording occurrences of diabetic ketoacidosis, severe hypoglycemia, and motor vehicle violations During follow-up, 50% of the subjects received booster training. RESULTS: During the first and last halves of both the baseline period and the follow-up period, dependent variables were generally stable. However, from baseline to follow-up, BGAT-2 led to 1) improved detection of hypoglycemia and hyperglycemia; 2) improved judgment regarding when to lower high BG, raise low BG, and not drive while hypoglycemic; 3) reduction in occurrence of diabetic ketoacidosis, severe hypoglycemia, and motor vehicle violations; and 4) improvement in terms of worry about hypoglycemia, quality of life, and diabetes knowledge. Reduction in severe hypoglycemia was not associated with a worsening of metabolic control (HbA1). The presence or absence of booster training did not differentially affect these benefits. CONCLUSION: BGAT has sustained broad-ranging benefits, independent of booster intervention.

Episodes of severe hypoglycemia in type 1 diabetes are preceded and followed within 48 hours by measurable disturbances in blood glucose.

This study quantifies blood glucose (BG) disturbances occurring before and after episodes of severe hypoglycemia (SH). For 6-8 months, 85 individuals with type 1 diabetes and a history of SH (age, 44+/-10 yr; 41 women and 44 men; duration of diabetes, 26+/-11 yr; hemoglobin A1c, 7.7+/-1.1%) used Lifescan One Touch BG meters for self-monitoring three to five times daily and recorded the date and time of SH episodes in diaries. For each subject, the timing of SH episodes was located in the temporal stream of SMBG readings recorded by the meter, and characteristics, including the Low BG index (LBGI), were computed in 24-h increments. In the 24-h period before the SH episode LBGI rose (P < 0.001), average BG was lower (P = 0.001), and BG variance increased (P = 0.001). In the 24 h after SH, LBGI and BGvariance remained elevated (P < 0.001), but average BG returned to baseline. These disturbances disappeared in 48 h. On the basis of LBGI we identified subjects at low, moderate, and high risk of SH, who reported, on the average, 1.7, 3.4, and 7.4 SH episodes (P < 0.005) during the study. In addition, we designed an algorithm that predicted 50% of all SH episodes that occurred in this subject group. We conclude that episodes of SH are preceded and followed by quantifiable BG disturbances, which could be used to devise warnings of imminent SH.

Progressive hypoglycemia's impact on driving simulation performance. Occurrence, awareness and correction.

OBJECTIVE: Progressive hypoglycemia leads to cognitive-motor and driving impairments. This study evaluated the blood glucose (BG) levels at which driving was impaired, impairment was detected, and corrective action was taken by subjects, along with the mechanisms underlying these three issues. RESEARCH DESIGN AND METHODS: There were 37 adults with type 1 diabetes who drove a simulator during continuous euglycemia and progressive hypoglycemia. During testing, driving performance, EEG, and corrective behaviors (drinking a soda or discontinuing driving) were continually monitored, and BG, symptom perception, and judgement concerning impairment were assessed every 5 min. Mean +/- SD euglycemia performance was used to quantify z scores for performance in three hypoglycemic ranges (4.0-3.4, 3.3-2.8, and <2.8 mmol/l). RESULTS: During all three hypoglycemic BG ranges, driving was significantly impaired, and subjects were aware of their impaired driving. However, corrective actions did not occur until BG was <2.8 mmol/l. Driving impairment was related to increased neurogenic symptoms and increased theta-wave activity. Awareness of impaired driving was associated with neuroglycopenic symptoms. increased beta-wave activity, and awareness of hypoglycemia. High beta and low theta activity and awareness of both hypoglycemia and the need to treat low BG influenced corrective behavior. CONCLUSIONS: Driving performance is significantly disrupted at relatively mild hypoglycemia, yet subjects demonstrated a hesitation to take corrective action. The longer treatment is delayed, the greater the neuroglycopenia (increased theta), which precludes corrective behaviors. Patients should treat themselves while driving as soon as low BG and/or impaired driving is suspected and should not begin driving when their BG is in the 5.0-4.0 mmol/l range without prophylactic treatment.

Biopsychobehavioral model of severe hypoglycemia. II. Understanding the risk of severe hypoglycemia.

OBJECTIVE: To evaluate the clinical/research utility of the biopsycho-behavioral model of severe hypoglycemia in differentiating patients with and without a history of severe hypoglycemia and in predicting occurrence of future severe hypoglycemia. RESEARCH DESIGN AND METHODS: A total of 93 adults with type 1 diabetes (mean age 35.8 years, duration of diabetes 16 +/- 10 years, HbA1 8.6 +/- 1.8%), 42 of whom had a recent history of recurrent severe hypoglycemia (SH) and 51 who did not (NoSH), used a handheld computer for 70 trials during 1 month recording cognitive-motor functioning, symptoms, blood glucose (BG) estimates, judgments concerning self-treatment of BG, actual BG readings, and actual treatment of low BG. For the next 6 months, patients recorded occurrence of severe hypoglycemia. RESULTS: SH patients demonstrated significantly more frequent and extreme low BG readings (low BG index), greater cognitive-motor impairments during hypoglycemia, fewer perceived symptoms of hypoglycemia, and poorer detection of hypoglycemia. SH patients were also less likely to treat their hypoglycemia with glucose and more likely to treat with general foods. Low BG index, magnitude of hypoglycemia-impaired ability to do mental subtraction, and awareness of neuroglycopenia, neurogenic symptoms, and hypoglycemia correlated separately with number of SH episodes in the subsequent 6 months. However, only low BG index, hypoglycemia-impaired ability to do mental subtraction, and awareness of hypoglycemia entered into a regression model predicting future severe hypoglycemia (R2 = 0.25, P < 0.001). CONCLUSIONS: Patients with a history of severe hypoglycemia differed on five of the seven steps of the biopsychobehavioral model of severe hypoglycemia. Helping patients with a recent history of severe hypoglycemia to reduce the frequency of their low-BG events, become more sensitive to early signs of neuroglycopenia and neurogenic symptoms, better recognize occurrence of low BG, and use fast-acting glucose more frequently in the treatment of low BG, may reduce occurrence of future severe hypoglycemia.

Hypoglycemia and the decision to drive a motor vehicle by persons with diabetes.

CONTEXT: Laboratory studies have shown impairments in driving performance among subjects with type 1 diabetes mellitus when their blood glucose (BG) level is between 2.6 and 3.6 mmol/L (47-65 mg/dL). However, to our knowledge, no data exist examining subjects' decisions to drive at various BG levels during their daily routine. OBJECTIVE: To examine type 1 diabetic subjects' decisions to drive during their daily routine based on perception of BG levels compared with actual measured BG levels. DESIGN AND SETTING: Two separate groups of patients were recruited 2 years apart from 4 academic medical centers. PARTICIPANTS: All subjects were adults with type 1 diabetes who were drivers and who performed at least 2 BG tests per day. Group 1 (initial) subjects (n = 65) had a mean (SD) age of 38.6 (8.9) years with a mean (SD) diabetes duration of 20.5 (10.6) years, were taking 38.8 (16.8) U/d of insulin, and had a mean (SD) glycosylated hemoglobin (HbA1) level of 10.0% (1.9%). Group 2 (replication) subjects (n = 93) were 35.8 (8.0) years old with a mean diabetes duration of 17.0 (10.6) years, were taking 40.0 (15.5) U/d of insulin, and had a mean (SD) HbA1 level of 8.5% (1.6%). Each subject used a handheld computer to record data on symptoms, cognitive function, insulin dosage, food, activity, estimated and actual BG levels, and whether he/she would drive. Data were entered 3 to 6 times per day for a total of 50 to 70 collections per subject during a 3- to 4-week period. MAIN OUTCOME MEASURES: Decisions to drive when subjects estimated their BG level to be less than 2.2 mmol/L (40 mg/dL), 2.2 to 2.8 mmol/L (40-50 mg/dL), 2.8 to 3.3 mmol/L (50-60 mg/dL), 3.3 to 3.9 mmol/L (60-70 mg/dL), 3.9 to 10 mmol/L (70-180 mg/dL), and more than 10 mmol/L (>180 mg/dL), and driving decisions when actual BG levels were in these ranges. RESULTS: Subjects stated they would drive 43% to 44% of the time when they estimated their BG level to be 3.3 to 3.9 mmol/L (60-70 mg/dL), and 38% to 47% of the time when their actual BG level was less than 2.2 mmol/L (40 mg/dL). Logistic regression analysis demonstrated that number of autonomic symptoms, degree of impairment on cognitive function tests, and BG level estimate predicted 76% to 80% of decisions to drive (P<.01 for all). Approximately 50% of subjects in each group decided to drive at least 50% of the time when their BG level was less than 3.9 mmol/L (70 mg/dL). CONCLUSIONS: Our data suggest that persons with type 1 diabetes may not judge correctly when their BG level is too low to permit safe driving and may consider driving with a low BG level even when they are aware of the low level. Health care professionals should counsel their patients about the risk of driving with hypoglycemia and the importance of measuring BG level before driving.

Biopsychobehavioral model of risk of severe hypoglycemia. Self-management behaviors.

OBJECTIVE: To identify self-management antecedents of low blood glucose (BG) (< 3.9 mmol/l) that might be easily recognized, treated, or avoided altogether. RESEARCH DESIGN AND METHODS: Ninety-three adults with type 1 diabetes (age, 35.8 +/- 8 years [mean +/- SD]; duration of diabetes, 17.0 +/- 11 years; daily insulin dose, 0.58 +/- 0.18 U/kg; and HbAlc, 8.6 +/- 1.8%) were recruited to participate in the study. Of the 93 subjects, 42 had a history of severe hypoglycemia (SH), defined as two or more hypoglycemic episodes in the preceding 12 months, and 51 subjects had no history of SH (No-SH) in the same time period. Before each of 70 BG measurements obtained over a 3-week period, subjects used a handheld computer to record whether their most recent insulin, food, and exercise was more than, less than, or the same as usual. Associations among self-management behaviors preceding BG readings < 3.9 mmol/l versus those preceding BG readings of 5.6-7.8 mmol/l were determined using chi 2 tests, analyses of variance, and logistic regression analyses. RESULTS: Analysis of 6,425 self-management/self-monitoring of BG events revealed that the usual amounts of insulin, food, and exercise preceded the events 58.3% of the time. No significant differences were observed for changes in insulin before readings of BG < 3.9 mmol/l versus 7.8 < BG > 5.6 mmol/l, but significantly less food (P < 0.01) was eaten and more exercise (P < 0.001) was performed before the low BG measurement. No interactions between SH and No-SH groups and management behaviors were observed. However, each of the three management variables entered significantly in a logistic model that predicted 61% of all readings of BG < 3.9 mmol/l. CONCLUSIONS: Subjects with a history of SH did not report managing their diabetes differently from those with no such history. Specifically, when low BG occurred, the preceding management behaviors, although predictive of low BG, were not different in SH and No-SH subjects. Overall, self-management behaviors did not distinguish SH from No-SH subjects. Thus, even though it might be beneficial for all patients to review their food and exercise management decisions to reduce their frequency of low BG, an educational intervention whose content stresses insulin, food, and exercise would be unlikely by itself to be sufficient to reduce the frequency of SH.

Assessment of risk for severe hypoglycemia among adults with IDDM: validation of the low blood glucose index.

OBJECTIVE: To evaluate the clinical/research utility of the low blood glucose index (LBGI), a measure of the risk of severe hypoglycemia (SH), based on self-monitoring of blood glucose (SMBG). RESEARCH DESIGN AND METHODS: There were 96 adults with IDDM (mean age 35+/-8 years, duration of diabetes 16+/-10 years, HbA1 8.6+/-1.8%), 43 of whom had a recent history of SH (53 did not), who used memory meters for 135+/-53 SMBG readings over a month, and then for the next 6 months recorded occurrence of SH. The SMBG data were mathematically transformed, and an LBGI was computed for each patient. RESULTS: The two patient groups did not differ with respect to HbA1, insulin units per day, average blood glucose (BG) and BG variability. Patients with history of SH demonstrated a higher LBGI (P < 0.0005) and a trend to be older with longer diabetes duration. Analysis of odds for future SH classified patients into low- (LBGI <2.5), moderate- (LBGI 2.5-5), and high- (LBGI >5) risk groups. Over the following 6 months low-, moderate-, and high-risk patients reported 0.4, 2.3, and 5.2 SH episodes, respectively (P = 0.001). The frequency of future SH was predicted by the LBGI and history of SH (R2 = 40%), while HbA1, age, duration of diabetes, and BG variability were not significant predictors. CONCLUSIONS: LBGI provides an accurate assessment of risk of SH. In the traditional relationship history of SH-to-future SH, LBGI may be the missing link that reflects present risk. Because it is based on SMBG records automatically stored by many reflectance meters, the LBGI is an effective and clinically useful on-line indicator for SH risk.

Stochastic model of self-regulation decision making exemplified by decisions concerning hypoglycemia.

The following sequence-internal condition --> symptom perception --> appraisal --> decision-models various symptom-based self-regulation processes. A formal mathematical model describes the first three steps by continuous variables and the decisions at the fourth step by binary variables. The stochastic transitions between the sequential steps are quantified by transition probabilities. The model is illustrated by blood glucose level estimation and detection and treatment of hypoglycemia in 78 patients with insulin-dependent diabetes mellitus. These patients made 50 to 70 data collection trials over 3 to 4 weeks recording perceived symptoms, cognitive-motor performance, subjective estimates of blood glucose, decisions about treatment of hypoglycemia, and driving. A statistical estimation of the model's parameters demonstrates the utility of this approach for understanding the awareness, detection, and treatment of hypoglycemia as a process of symptom-based decision making.

Symmetrization of the blood glucose measurement scale and its applications.

OBJECTIVE: To introduce a data transformation that enhances the power of blood glucose data analyses. RESEARCH DESIGN AND METHODS: In the standard blood glucose scale, hypoglycemia (blood glucose, < 3.9 mmol/l) and hyperglycemia (blood glucose, > 10 mmol/l) have very different ranges, and euglycemia is not central in the entire blood glucose range (1.1-33.3 mmol/l). Consequently, the scale is not symmetric and its clinical center (blood glucose, 6-7 mmol/l) is distant from its numerical center (blood glucose, 17 mmol/l). As a result, when blood glucose readings are analyzed, the assumptions of many parametric statistics are routinely violated. We propose a logarithmic data transformation that matches the clinical and numerical center of the blood glucose scale, thus making the transformed data symmetric. RESULTS: The transformation normalized 203 out of 205 data samples containing 13,584 blood glucose readings of 127 type 1 diabetic individuals. An example illustrates that the mean and standard deviation based on transformed, rather than on raw, data better described subject's blood glucose distribution. Based on transformed data: 1) the low blood glucose index predicted the occurrence of severe hypoglycemia, while the raw blood glucose data (and glycosylated hemoglobin levels) did not; 2) the high blood glucose index correlated with the subjects' glycosylated hemoglobin (r = 0.63, P < 0.001); and 3) the low plus high blood glucose index was more sensitive than the raw data to a treatment (blood glucose awareness training) designed to reduce the range of blood glucose fluctuations. CONCLUSIONS: Using symmetrized, instead of raw, blood glucose data strengthens the existing data analysis procedures and allows for the development of new statistical techniques. It is proposed that raw blood glucose data should be routinely transformed to a symmetric distribution before using parametric statistics.

The psychosocial impact of severe hypoglycemic episodes on spouses of patients with IDDM.

OBJECTIVE: No previous studies have examined the psychosocial impact of severe hypoglycemic episodes in IDDM patients on their spouses. This study compared spouses of IDDM patients with and without a history of recent severe hypoglycemia (SH) using traditional measures of psychosocial status and marital conflict, as well as diabetes-specific measures. RESEARCH DESIGN AND METHODS: A total of 61 nondiabetic spouses (23 wives and 38 husbands) of IDDM patients participated in the study. Spouses completed a battery of traditional psychometric measures (depression, anxiety, marital conflict) and diabetes-specific measures (fear of hypoglycemia, marital conflict over diabetes, sleep disturbance caused by hypoglycemia). Scores of spouses of IDDM patients with and without a recent history of SH were compared with t tests. RESULTS: Spouses of IDDM patients with and without a recent history of SH showed no differences on traditional psychometric measures of depression, anxiety, and marital conflict. However, spouses of patients with a recent history of SH showed significantly more fear of hypoglycemia, marital conflict about diabetes management, and sleep disturbances caused by hypoglycemia. Exploratory analyses of variance (ANOVAs) found no differences on psychometric measures between wives and husbands, with the exception that husbands of SH patients reported more sleep disturbance. Nondiabetic spouses, on average, showed greater fear of hypoglycemia than their diabetic partners. CONCLUSIONS: Although SH in IDDM patients can have a significant impact on the psychosocial status of their spouses, in this study the negative impact was restricted to areas of life that are directly related to diabetes and its management. Thus, SH per se is not necessarily associated with significant increases in spousal anxiety, depression, or marital conflict, but may be associated with types of diabetes-specific psychosocial distress that are not easily identified by traditional psychometric measures.

A biopsychobehavioral model of risk of severe hypoglycemia.

Severe hypoglycemia (SH) is a significant problem for many patients with type I diabetes and presents a major barrier to optimal diabetes control. A critical task facing diabetes research is to understand, predict, and reduce the risk of SH in insulin-treated patients. The purpose of this article is to propose a biopsychobehavioral model of SH risk that integrates and extends previously proposed models. Current biological and psychological models of SH risk, which focus on hormonal counterregulation and symptom awareness, are reviewed. The limitations of these models are also discussed, including their failure to recognize important psychological and behavioral processes that contribute to SH risk. Specifically, the biopsychobehavioral model includes patients' decision-making, judgment, and behavioral responses as significant predictors of SH risk. The proposed model is comprised of seven steps: 1) physiological and behavioral precursors to low blood glucose (BG), 2) low BG occurrence, 3) hormonal and neurological responses to low BG, 4) awareness of symptoms caused by hormonal and neurological changes, 5) detection of low BG, 6) decision-making and judgment, and 7) behavioral response. The model has several advantages, including the ability to mathematically calculate the transitional probabilities from each step to the next as well as the ability to describe SH risk in both hypoglycemia-aware and hypoglycemia-unaware patients. Research findings supporting the biopsychobehavioral model are presented, and its empirical and clinical implications are discussed.

The relationship between nonroutine use of insulin, food, and exercise and the occurrence of hypoglycemia in adults with IDDM and varying degrees of hypoglycemic awareness and metabolic control.

The purpose of this study was to determine objectively the relationships between changes in the usual amount of insulin injected, food eaten, and exercise performed, and the subsequent occurrence of low blood glucose (< 3.9 mM) in adults with IDDM and varying degrees of hypoglycemic awareness and metabolic control. Subjects used a handheld computer to record whether their most recent insulin, food, and exercise had been omitted or were greater than, less than, or about the same as usual following every measured blood glucose level of < 3.9 mM and > 5.6 mM. Responses for each self-management behavior were compared for the two blood glucose ranges. Food was omitted more frequently prior to a low glucose reading and exercise was omitted more frequently prior to a high glucose reading. More insulin, less food, and more exercise each were associated with low glucose levels. These findings underscore the importance of traditional diabetes education.