Pitfalls of insulin pump clocks: technical glitches that may potentially affect medical care in patients with diabetes.

The objective was to raise awareness about the importance of ensuring that insulin pumps internal clocks are set up correctly at all times. This is a very important safety issue because all commercially available insulin pumps are not GPS-enabled (though this is controversial), nor equipped with automatically adjusting internal clocks. Special attention is paid to how basal and bolus dose errors can be introduced by daylight savings time changes, travel across time zones, and am-pm clock errors. Correct setting of insulin pump internal clock is crucial for appropriate insulin delivery. A comprehensive literature review is provided, as are illustrative cases. Incorrect setting can potentially result in incorrect insulin delivery, with potential harmful consequences, if too much or too little insulin is delivered. Daylight saving time changes may not significantly affect basal insulin delivery, given the triviality of the time difference. However, bolus insulin doses can be dramatically affected. Such problems may occur when pump wearers have large variations in their insulin to carb ratio, especially if they forget to change their pump clock in the spring. More worrisome than daylight saving time change is the am-pm clock setting. If this setting is set up incorrectly, both basal rates and bolus doses will be affected. Appropriate insulin delivery through insulin pumps requires correct correlation between dose settings and internal clock time settings. Because insulin pumps are not GPS-enabled or automatically time-adjusting, extra caution should be practiced by patients to ensure correct time settings at all times. Clinicians and diabetes educators should verify the date/time of insulin pumps during patients' visits, and should remind their patients to always verify these settings.

Update on diabetes diagnosis: a historical review of the dilemma of the diagnostic utility of glycohemoglobin A1c and a proposal for a combined glucose-A1c diagnostic method.

The role of glycohemoglobin A1c (A1c) for the diagnosis of diabetes has been debated for over three decades. Recently, the American Diabetes Association (ADA) has recommended adding A1c as an additional criterion for diabetes diagnosis. In view of the continued debate about the diagnostic utility of A1c, and in view of the unabated burden of undiagnosed diabetes, the search for alternative diagnostic methods is discussed. A historical literature review is provided, in view of the new ADA diagnostic guidelines, and a proposal is provided for combining A1c and a glucose measurement as a diagnostic alternative/adjunct to the use of a single criterion. This proposal is based on the non-overlapping of the advantages and disadvantages of these individual tests. The cost-effectiveness of this method remains to be tested.

Role of ultrasonography in the differential diagnosis of thyrotoxicosis: a noninvasive, cost-effective, and widely available but underutilized diagnostic tool.

OBJECTIVE: To explore the use of ultrasonography as a diagnostic alternative to the traditional "gold standard" imaging study of nuclear scintigraphy in the evaluation of thyrotoxicosis. METHODS: We review the relevant literature and share our own experience to highlight the promising role of ultrasonography in thyrotoxicosis. In addition, we present a diagnostic algorithm suggesting liberal use of ultrasonography in the evaluation of thyrotoxicosis. RESULTS: Ultrasonography has proved effective not only in the differentiation of Graves disease from other types and causes of thyrotoxicosis but also in the detection of subtle thyroid nodules. The latter role is emphasized in light of the recent observation of an increased risk of occurrence of papillary thyroid carcinoma in patients with Graves disease. CONCLUSION: Ultrasonography is a cost-effective, noninvasive, portable, and safe imaging modality in the evaluation of thyrotoxicosis, both for physiologic assessment and for detection of nonpalpable thyroid cancers that may elude identification on physical examination and nuclear imaging studies. Although thyroid scintigraphy remains a standard radiologic study, thyroid ultrasonography can be a practical alternative in many cases and the primary imaging modality in some situations such as during pregnancy and lactation and for evaluation and management of amiodarone-induced thyrotoxicosis.

Identifying prediabetes using fasting insulin levels.

OBJECTIVE: To determine whether patients with prediabetes can be accurately and easily identified in clinical settings using a predictive clinical and laboratory model. METHODS: This retrospective study examined demographic and laboratory data from patients who had undergone 2-hour glucose testing for suspected prediabetes or diabetes between 2000 and 2004. Patients who met the diagnostic criteria for diabetes mellitus were excluded. Prediabetes was defined as a fasting glucose concentration > or = 100 mg/dL and < or = 125 mg/dL or a 2-hour postprandial glucose concentration > or = 140 mg/dL and < 200 mg/dL. Multivariate logistic regression was conducted to identify calculated or measured clinical and laboratory attributes that predict the presence of prediabetes, including fasting insulin quartiles, homeostasis model assessment of insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index. RESULTS: Of 965 patients, 287 (29.7%) had prediabetes. The study population primarily consisted of white, obese, female patients. A multivariate model revealed that compared with the referent lowest quartile of fasting insulin (mu = 4.9 [+/-SD] +/-1.2 microIU/mL), subsequent insulin quartiles increased the likelihood of identifying prediabetes (quartile 2: mu = 8.0 +/-0.8 microIU/mL, odds ratio [OR] = 2.076, confidence interval [CI] = 1.241-3.273; quartile 3: mu = 12.2 +/-1.7 microIU/mL, OR = 3.151, CI = 1.981-5.015; quartile 4: mu = 25.9 +/-12.4 microIU/mL, OR = 5.035, CI = 3.122-8.122). Older age and increased diastolic blood pressure also contributed modestly to this model. Further analysis using the area under the curve revealed that at a fasting insulin level > 9.0 microIU/mL, prediabetes would be correctly identified in 80% of affected patients. A second model revealed that increased HOMA-IR index (OR = 1.303, CI = 1.205-1.410) and older age (OR = 1.037, CI = 1.024-1.05) predicted prediabetes. CONCLUSIONS: The most robust model, which used fasting insulin levels, may provide the most utility as a clinical tool because the highest quartiles suggest significantly greater likelihood of identifying prediabetes.

Hemoglobin A1c: past, present and future.

Hemoglobin A1c (HbA1c) has been used for decades to monitor the control of glycemia in diabetes. Although HbA1cis currently undergoing a reassessment, and major developments have been underway in recent years, HbA1c is not recommended at present for diabetes screening or diagnosis. The objective of this review is to summarize the recent developments and to review a potential diagnostic role for HbA1c. Implementation of changes in HbA1c results and units of measurements have been suggested for the purpose of test standardization. These include lower reference ranges (by about 1.5-2 points) and measurement units expressed in percentage (%), as mg/dL (mmol/L) or mmol/mol (or a combination of these units). In diabetes screening and diagnosis, the current diagnostic guidelines use measurement of plasma glucose either fasting or after glucose load. These diagnostic methods have shortcomings warranting a potential diagnostic role for HbA1c. While recent developments in HbA1c methodologies are acknowledged, it is not yet known which changes will be implemented, and how soon. Given the recent literature supporting HbA1c diagnostic abilities, and given the shortcomings of the current guidelines, it is possible that a diagnostic role for HbA1c may be considered in future practice guidelines, globally. Very recently, the first of such recommendations has been proposed by an expert panel, as announced by the US Endocrine Society.

Glycohemoglobin A1c: A promising screening tool in gestational diabetes mellitus.

CONTEXT: Current screening tests for gestational diabetes mellitus (GDM) are inconvenient. Therefore, alternative screening tests for GDM are desirable. The use of glycohemoglobin A1c (HbA1c) in screening for GDM remains controversial. AIM: We undertook this study to evaluate the utility of HbA1c in screening for GDM. SETTINGS AND DESIGN: Retrospective study in a tertiary teaching hospital. MATERIALS AND METHODS: Laboratory records were reviewed to identify pregnant women who underwent both oral glucose tolerance test (OGTT) and HbA1c measurements over a 16-months period. The association of OGTT with HbA1c was evaluated. STATISTICAL ANALYSIS USED: Data were collected using SPSS software. Comparisons of the means and calculations of sensitivities were performed. RESULTS: Of 145 eligible patients, 124 had GDM and 21 patients did not, per OGTT. The percentages of patients with HbA1c values (reference range of 4.8%-6.0%) equal to or above sequential cut-point values of 5.0%, 5.5%, 6.0%, 6.5% and 7.0% (i.e., sensitivity values) were 100%, 98.4%, 87.1%, 62.9% and 39.5%, respectively. The mean HbA1c of the patients with GDM was 6.9 + 0.8% compared to 6.4 + 0.6% for those without GDM (P< 0.006). At an arbitrary cut-off value of 6.0% (the upper limit of normal), HbA1c would have picked up 87.1% of patients with GDM. CONCLUSIONS: This study suggests that HbA1c is a reasonably sensitive screening measure of GDM in this high-risk population. Acknowledging limitations resulting from the study design, further prospective studies are warranted to verify this conclusion, and to evaluate the specificity of HbA1c as a screening test for GDM.