Detection of subsequent episodes of gestational diabetes mellitus: a need for specific guidelines

Guidelines for detection of individuals with gestational diabetes mellitus (GDM) indicate that glucose testing for women with a history of GDM should occur as soon as feasible with retesting of an initially negative screen to occur between the 24th and 28th week of gestation. The aim of this study was to evaluate medical records for individuals enrolled in a GDM management program that presented with two subsequent pregnancies with GDM and to determine if more specific guidelines for detection are needed. Records (n=60) from both pregnancies were reviewed for gestational age at enrollment, delivery, and when insulin was started, infant birth weights and complications (e.g., hypoglycemia), and maternal complications (e.g., emergency cesarean section). Over half [33/60 (55%)] of the women required insulin during both pregnancies, while 16.7% (10/60) required insulin during the second enrollment for GDM but not the first. For those requiring insulin during both pregnancies, 88% (29/33) required it earlier during the subsequent pregnancy (31.5+/-2.7 vs. 21.6+/-8.4 weeks of gestation, P<.001). During the subsequent pregnancy, approximately 1/2 of the women requiring insulin needed it before the 24th week of gestation while 1/3 required it by the 15th week. Also during the subsequent pregnancy, neonate birth weights declined (3494+/-521 vs. 3356+/-515 g, P<.05) and there were fewer complications. Given that approximately 70% of the women required insulin therapy during a subsequent GDM pregnancy and that this therapy was on average necessary by the 22nd week of gestation, we recommend that specific guidelines be established with a definitive time frame determined for the detection of repeat episodes of GDM.

Effect of treatment with losartan on cardiovascular autonomic and large sensory nerve fiber function in individuals with diabetes mellitus: a 1-year randomized, controlled trial

This study evaluated the effect of losartan, an angiotensin II receptor antagonist, on cardiovascular autonomic function and large sensory nerve fiber function in individuals with diabetes mellitus. In a double-blind placebo-controlled trial, individuals were randomly assigned to treatment with a daily oral dose of 50-mg losartan (n=24) or placebo (n=20) for 12 months. Tests of cardiovascular autonomic function (i.e., RR-variation during deep breathing and the Valsalva maneuver) and of large sensory nerve fiber function (i.e., vibratory thresholds) were measured at baseline and at 12 months. No significant difference at baseline was found for duration of diabetes, glycemic control, blood pressure, or body mass index (BMI) between the two groups. After 12 months, the decline in RR-variation that occurs over time appeared to be less for those taking losartan. There was, however, no statistically significant change in the results for any of the tests of cardiovascular autonomic function or vibratory thresholds between the groups. Multivariate analyses in the losartan study group revealed an independent association of duration of diabetes, change in (reduced) systolic blood pressure (SBP), and improved vibratory thresholds. This association was particularly noted for women. Pharmacologic agents may affect cardiovascular autonomic function by favorable or detrimental changes in the electrophysiology of the heart. The results of this study indicate that, although losartan may have slowed the normal decline in RR-variation, it did not result in any significant improvement in cardiovascular autonomic nerve fiber function. An association of vibratory thresholds and SBP was observed.

The association between cardiovascular autonomic neuropathy and mortality in individuals with diabetes: a meta-analysis

OBJECTIVE

To examine by meta-analysis the relationship between cardiovascular autonomic neuropathy (CAN) and risk of mortality in individuals with diabetes.

RESEARCH DESIGN AND METHODS

We searched Medline for English-language articles published from 1966 to 2001. Fifteen studies having a baseline assessment of cardiovascular autonomic function and mortality follow-up were identified. The analyses were stratified according to whether a single abnormality or two or more measures of cardiovascular autonomic function were used to define CAN. A global measure of association (i.e., relative risk) was generated for each group by pooling estimates across the studies using the Mantel-Haenszel procedure.

RESULTS

CAN was significantly associated with subsequent mortality in both groups, although the magnitude of the association was stronger for those studies for which two or more measures were used to define CAN. The pooled relative risk for studies that defined CAN with the presence of two or more abnormalities was 3.45 (95% CI 2.66-4.47; P < 0.001) compared with 1.20 (1.02-1.41; P = 0.03) for studies that used one measure.

CONCLUSIONS

These results support an association between CAN and increased risk of mortality. The stronger association observed in studies defining CAN by the presence of two or more abnormalities may be due to more severe autonomic dysfunction in these subjects or a higher frequency of other comorbid complications that contributed to their higher mortality risk. Future studies should evaluate whether early identification of subjects with CAN can lead to a reduction in mortality.

Diabetic autonomic neuropathy

Diabetic autonomic neuropathy (DAN) is a serious and common complication of diabetes. Despite its relationship to an increased risk of cardiovascular mortality and its association with multiple symptoms and impairments, the significance of DAN has not been fully appreciated. The reported prevalence of DAN varies widely depending on the cohort studied and the methods of assessment. In randomly selected cohorts of asymptomatic individuals with diabetes, approximately 20% had abnormal cardiovascular autonomic function. DAN frequently coexists with other peripheral neuropathies and other diabetic complications, but DAN may be isolated, frequently preceding the detection of other complications. Major clinical manifestations of DAN include resting tachycardia, exercise intolerance, orthostatic hypotension, constipation, gastroparesis, erectile dysfunction, sudomotor dysfunction, impaired neurovascular function, "brittle diabetes," and hypoglycemic autonomic failure. DAN may affect many organ systems throughout the body (e.g., gastrointestinal [GI], genitourinary, and cardiovascular). GI disturbances (e.g., esophageal enteropathy, gastroparesis, constipation, diarrhea, and fecal incontinence) are common, and any section of the GI tract may be affected. Gastroparesis should be suspected in individuals with erratic glucose control. Upper-GI symptoms should lead to consideration of all possible causes, including autonomic dysfunction. Whereas a radiographic gastric emptying study can definitively establish the diagnosis of gastroparesis, a reasonable approach is to exclude autonomic dysfunction and other known causes of these upper-GI symptoms. Constipation is the most common lower-GI symptom but can alternate with episodes of diarrhea. Diagnostic approaches should rule out autonomic dysfunction and the well-known causes such as neoplasia. Occasionally, anorectal manometry and other specialized tests typically performed by the gastroenterologist may be helpful. DAN is also associated with genitourinary tract disturbances including bladder and/or sexual dysfunction. Evaluation of bladder dysfunction should be performed for individuals with diabetes who have recurrent urinary tract infections, pyelonephritis, incontinence, or a palpable bladder. Specialized assessment of bladder dysfunction will typically be performed by a urologist. In men, DAN may cause loss of penile erection and/or retrograde ejaculation. A complete workup for erectile dysfunction in men should include history (medical and sexual); psychological evaluation; hormone levels; measurement of nocturnal penile tumescence; tests to assess penile, pelvic, and spinal nerve function; cardiovascular autonomic function tests; and measurement of penile and brachial blood pressure. Neurovascular dysfunction resulting from DAN contributes to a wide spectrum of clinical disorders including erectile dysfunction, loss of skin integrity, and abnormal vascular reflexes. Disruption of microvascular skin blood flow and sudomotor function may be among the earliest manifestations of DAN and lead to dry skin, loss of sweating, and the development of fissures and cracks that allow microorganisms to enter. These changes ultimately contribute to the development of ulcers, gangrene, and limb loss. Various aspects of neurovascular function can be evaluated with specialized tests, but generally these have not been well standardized and have limited clinical utility. Cardiovascular autonomic neuropathy (CAN) is the most studied and clinically important form of DAN. Meta-analyses of published data demonstrate that reduced cardiovascular autonomic function as measured by heart rate variability (HRV) is strongly (i.e., relative risk is doubled) associated with an increased risk of silent myocardial ischemia and mortality. The determination of the presence of CAN is usually based on a battery of autonomic function tests rather than just on one test. Proceedings from a consensus conference in 1992 recommended that three tests (R-R variation, Valsalva maneuver, and postural blood pressure testing)or longitudinal testing of the cardiovascular autonomic system. Other forms of autonomic neuropathy can be evaluated with specialized tests, but these are less standardized and less available than commonly used tests of cardiovascular autonomic function, which quantify loss of HRV. Interpretability of serial HRV testing requires accurate, precise, and reproducible procedures that use established physiological maneuvers. The battery of three recommended tests for assessing CAN is readily performed in the average clinic, hospital, or diagnostic center with the use of available technology. Measurement of HRV at the time of diagnosis of type 2 diabetes and within 5 years after diagnosis of type 1 diabetes (unless an individual has symptoms suggestive of autonomic dysfunction earlier) serves to establish a baseline, with which 1-year interval tests can be compared. Regular HRV testing provides early detection and thereby promotes timely diagnostic and therapeutic interventions. HRV testing may also facilitate differential diagnosis and the attribution of symptoms (e.g., erectile dysfunction, dyspepsia, and dizziness) to autonomic dysfunction. Finally, knowledge of early autonomic dysfunction can encourage patient and physician to improve metabolic control and to use therapies such as ACE inhibitors and beta-blockers, proven to be effective for patients with CAN.

Do plasminogen activator inhibitor (PAI-1) or tissue plasminogen activator PAI-1 complexes predict complications in Type 1 diabetes: the Pittsburgh Epidemiology of Diabetes Complications Study

AIMS

To examine the predictive power of plasminogen activator inhibitor-1 (PAI-1) and the complexes it forms with tissue plasminogen activator (tPA-PAI-1) for the two major Type 1 diabetes (T1D) complications (coronary artery disease (CAD) and overt nephropathy) in the context of standard risk factors.

METHODS

Observational prospective study of 454 participants with childhood onset (< 17 years) T1D, aged 18+ years at baseline. PAI-1 and tPA-PAI-1 were determined using ELISA methodology. Follow-up (6 years) was limited to 382 individuals for CAD and 294 individuals for overt nephropathy, after excluding baseline cases. Total, HDL and LDL-cholesterol, triglycerides, HbA1, blood pressure, body mass index (BMI), waist-hip ratio (WHR), leucocyte count, Beck depression score and fibrinogen were also examined.

RESULTS

The 56 incident cases of CAD had marginally lower PAI-1 and higher tPA-PAI-1 levels compared with those free of CAD. However, marginally higher PAI-1 and significantly higher tPA-PAI-1 (P = 0.04) levels were seen in those who developed nephropathy. After controlling for age, both PAI-1 and tPA-PAI-1 showed significant negative correlations with HDL-cholesterol, and positive correlations with triglycerides, WHR, HbA1 and fibrinogen. tPA-PAI-1 was also positively correlated with total and LDL-cholesterol. In multivariate analyses, neither PAI-1 nor tPA-PAI-1 was an independent predictor of CAD or overt nephropathy.

CONCLUSIONS

These results suggest little association between PAI-1 and later CAD in patients with T1D. However, tPA-PAI-1 complexes may be involved in the pathogenesis of overt nephropathy.

Obesity is not a confounding factor for performing autonomic function tests in individuals with diabetes mellitus

AIM

Cardiovascular autonomic neuropathy is a serious complication of diabetes mellitus. Previous studies have revealed conflicting results with regard to the role of obesity and its effect on the performance of tests (e.g. RR-variation during deep breathing) for the determination of the presence of cardiovascular autonomic dysfunction. The objective of this study was to determine if obesity affects the performance and the reproducibility of autonomic function tests.

METHODS

This cross-sectional study included 159 diabetic individuals. Autonomic function tests included: RR-variation during deep breathing and the Valsalva ratio. These tests were assessed using the ANS2000 ECG Monitor and Respiration Pacer. RR-variation was measured by vector analysis (i.e. mean circular resultant, MCR). Reproducibility of the autonomic function tests was assessed by determining the coefficient of variation (CV) on repeat testing.

RESULTS

Using cut-off points to describe normal weight (body mass index (b.m.i.) < or = 25 kg/m(2)), overweight (b.m.i. 25.01-30 kg/m(2)), obese (b.m.i. 30.01-40 kg/m(2)), and morbidly obese (b.m.i. > or = 40.1 kg/m(2)), no difference was found for the MCR, Valsalva ratio, CV of the MCR, or CV of the Valsalva ratio among the various weight levels for individuals with type 1 or type 2 diabetes.

CONCLUSIONS

The results of this study indicate that obesity is not a confounding factor in the performance of autonomic function tests. Likewise, the reproducibility of autonomic function testing is not affected by obesity. Assessment of autonomic function is important for obese and non-obese individuals given that reduced RR-variation is associated with exercise intolerance, intraoperative cardiovascular lability and increased risk of mortality.

Cardiovascular autonomic neuropathy (expiration and inspiration ratio) in type 1 diabetes. Incidence and predictors

The pathogenesis of diabetic neuropathy is poorly understood. In this prospective study, we investigated the incidence rate and potential predictors for cardiovascular autonomic neuropathy (CAN) in a cohort of childhood-onset type 1 diabetic patients. Subjects from the Epidemiology of Diabetes Complications Study were examined at baseline and then biennially. CAN was diagnosed by abnormal (</=1. 1) expiration/inspiration ratio during deep breathing. During the 4. 7-year mean follow-up period, CAN developed in 104 patients from the 373 subjects who were free of CAN at baseline and provided follow-up data, an incidence-density of 5.9 cases/100 person-years. Cox proportional hazard modeling showed age (relative risk [RR]=2.15, p=0.0001), HbA1 (RR=1.50, p=0.0002) and nephropathy (albumin excretion >200 ug/min) (RR=2.46, p=0.0001) to be significant independent predictors. Hypertension was, however, predictive if nephropathy was not included in the model. We conclude that beyond age and poor glycemic control, nephropathy is a significant risk factor for CAN and this association may explain some of the increased mortality seen in CAN.

Over-the-counter yellow ultraviolet light protective lenses: any benefit for individuals with diabetes mellitus?

The use of yellow UV protective lenses did improve some individual's ability to see even under artificial and controlled circumstances. Each test, although given in random order, cannot be interpreted to demonstrate the full range of benefit. The improvement for most was modest. Any improvement was most likely due to increased contrast. Light of a short wavelength is scattered more than long wavelength light. The yellow UV protective lenses block light of a short wavelength, thus reducing scatter and increasing contrast. Therefore, patients with visual problems of increased scatter would be expected to demonstrate the greatest improvement. We did not test for the duration of benefit. Subjective reports, from other patients, who have routinely used these lenses (only yellow lens-naive patients were included in the trial) suggest that the benefit increased with duration of use. Patients who routinely use the yellow UV protective lenses state that due to the increased contrast, they squint less. This seems to be most true at dusk. These regular users note that both their eyes are less tired and driving, in particular, is less stressful with the use of yellow lenses. The small benefit might conceivably be magnified in a real world setting. Given that the lenses cost only $10 to $15 and can be purchased in any sporting goods store, even our small measured improvement is likely to be worthwhile. Finally, patients were tested with "off-the-shelf" yellow lenses. To benefit patients the study was designed for their convenience and the low purchase price. The color of the lenses can be chosen to maximize the desired effect. We did not test various wavelength yellow lenses. Consequently, there may be better, albeit more expensive, yellow/orange lenses which might be designed explicitly for this purpose. In summary, the use of these yellow "sunglasses" might provide some improvement in sight for diabetic patients while keeping expense to a minimum.

Intravenous insulin infusion therapies for postoperative coronary artery bypass graft patients

BACKGROUND

Hyperglycemia is very common in postoperative coronary artery bypass graft patients. Although sliding scale insulin therapy is often used, there is no standard of care for the management of hyperglycemia.

METHODS

Different intravenous insulin therapies were used in three consecutive sets of hyperglycemic postoperative coronary artery bypass graft patients. The first method was a sliding scale intravenous insulin regimen beginning with four units/hr, and increasing by four units/hr each hourly bedside arterial whole blood glucose measurement greater than 250 mg/dL (13.9 mmol/L) (n = 58). The second and third methods were constant insulin infusions at a rate of eight units (n = 60) and 20 units/hr (n = 51) respectively. Insulin infusions were reduced to two units/hr when the glucose concentration decreased to 150-250 mg/dL (8.3-13.9 mmol/L), and was stopped when it fell below 150 mg/dL (8.3 mmol/L).

RESULTS

Thirty percent of patients undergoing coronary artery bypass grafting had a diagnosis of diabetes mellitus. Forty-eight percent of all patients had a glucose value greater than 250 mg/dL (13.9 mmol/L) within the first 24 hours postoperatively. The three intravenous insulin infusion regimens produced similar control of arterial whole blood glucose concentrations. Patients with high initial glucose concentrations (greater than 400 mg/dL) (22.2 mmol/L) required intravenous insulin therapy for ten or more hours before attaining the target range of 151-250 mg/dL (8.3-13.9 mmol/L).

CONCLUSIONS

Constant-rate intravenous insulin therapy is effective in lowering arterial whole blood glucose concentrations in postoperative coronary artery bypass graft patients. Initiation of intravenous insulin therapy at lower glucose values reduces the time necessary for the infusion.

The new diagnosis and classification of diabetes mellitus

We are in the midst of an epidemic of diabetes, and the prevalence appears to be especially marked within Delaware. To prevent tragic long-term complications of diabetes, and to minimize the enormous costs associated with treating them, an emphasis must be placed on the early diagnosis and aggressive management of diabetes. The changes in the classification, diagnosis and screening for diabetes should help to redirect the focus to one of preventive care.

Vibratory thresholds correlation with systolic blood pressure in diabetic women

Previous studies have suggested a potential association of elevated blood pressure (BP) and the development of diabetic neuropathy for individuals with insulin-dependent diabetes mellitus. In this study, we examined an association between BP and vibratory thresholds (assessment modality of large sensory nerve fiber function) for 33 participants with non-insulin-dependent diabetes mellitus. There were 19 women and 14 men aged 58 +/- 7 (mean +/- SD) years, with diabetes duration of 7 +/- 6 years and a body mass index of 29 +/- 5 kg/m2. None of the individuals were taking any medications that lower BP and all were negative for the presence of microalbuminuria. Vibratory thresholds were determined at three visits using a two-alternative, forced-choice procedure. BP was assessed by 24-h ambulatory BP monitoring. As expected, vibratory thresholds were higher for men than for women (6.3 +/- 4 v 4.2 +/- 3 vibration units) but there was no statistical difference after controlling for height. In multivariate analyses with vibratory thresholds as the dependent variable, duration of diabetes (P < 0.01), age (P < .01) and systolic BP (SBP) (P < .01) explained approximately 70% of the overall variability of the gender-specific (ie, female) model. The variability was similar (ie, 70% to 73%) no matter which SBP measure was available for modeling. In terms of diastolic blood pressure (DBP) measures, only the percentage of abnormal readings (ie, > 90 mm Hg) for day DBP was found to be independently associated with vibratory thresholds for women. The association of BP and large sensory nerve fiber dysfunction for nonnephropathic diabetic women found in this cross-sectional study warrants further investigation.

Do tissue plasminogen activator-plasminogen activator inhibitor-1 complexes relate to the complications of insulin-dependent diabetes mellitus? Pittsburgh Epidemiology of Diabetes Complications Study

The purpose of this study was to examine the potential relationship of tissue plasminogen activator-plasminogen activator inhibitor-1 (tPA-PAI-1) complexes and diabetic complications in individuals with insulin-dependent diabetes mellitus (IDDM). To address this issue, data from the third follow-up visit of participants in the Epidemiology of Diabetes Complications (EDC) study were examined. There were 454 participants, aged 32 +/- 8 years, with duration of IDDM of 23 +/- 8 years. Higher levels of tPA-PAI-1 complexes were seen for both men and women with IDDM complications. Specifically, statistically significant differences were seen in men with neuropathy (1.81 +/- 0.9 versus 1.42 +/- 0.8 ng/mL, p < 0.01), microalbuminuria (1.77 +/- 1.1 versus 1.35 +/- 0.6 ng/mL, p < 0.01), retinopathy (1.67 +/- 0.9 versus 1.43 +/- 0.8 ng/mL, p < 0.05), and lower extremity arterial disease (1.93 +/- 0.7 versus 1.50 +/- 0.9 ng/mL, p < 0.05) versus men without the particular complication. In women, higher complex levels were shown for those with retinopathy (1.51 +/- 0.8 versus 1.29 +/- 1.1 ng/mL, p < 0.01). Potential mechanisms for the relationship of higher complex levels and diabetic complications include an altered fibrinolytic response and/or insulin resistance. Because the results are cross sectional, it cannot be established whether the higher concentration of complexes is a result of the presence of complications or are antecedent. Prospective follow-up will be required to determine if tPA-PAI-1 complexes are predictive of the development of IDDM complications.

Hypertension as a risk factor for diabetic neuropathy: a prospective study

The pathogeneses of diabetic neuropathy is still unclear. This study prospectively investigated the risk factors for distal symmetrical polyneuropathy (DSP) in a cohort of childhood-onset IDDM patients. Subjects from the Epidemiology of Diabetes Complications (EDC) Study were clinically examined at baseline and then biennially. DSP was diagnosed by a combination of clinical criteria, symptoms and signs (Diabetes Control and Complications Trial [DCCT] exam), and quantitative sensory threshold (QST). Among the 463 (70.4%) subjects who were free of DSP at baseline, 453 (97.8%) participated in at least one biennial reexamination during the first 6 years of follow-up and were included in the current analysis. A total of 68 (15.0%) subjects developed DSP in 6 years, giving a cumulative probability of 0.29. The Cox proportional hazards model shows that longer IDDM duration, hypertension, poor glycemic control, height, and smoking were all independent predictors of the incidence of DSP (all P < 0.0001, except for smoking for which P = 0.03). Hypertension showed the greatest impact on the development of DSP for individuals with either short or long IDDM duration. This study confirms some risk factors for DSP found in cross-sectional studies and suggests a strong relationship between hypertension and DSP. The results indicate that in addition to good glycemic control, avoidance of smoking and good blood pressure control may be helpful in preventing or delaying the onset of DSP in IDDM patients.

A cross-sectional study comparing two quantitative sensory testing devices in individuals with diabetes

OBJECTIVE

This study was designed to compare circumference discrimination thresholds, as assessed by the Tacticon (Tacticon, Inc., Westtown, PA), a new quantitative sensory testing (QST) device, with vibratory thresholds, an assessment modality of large sensory nerve fibers, in individuals with diabetes.

RESEARCH DESIGN AND METHODS

In this study, 150 individuals with diabetes were evaluated. Vibratory thresholds and circumference discrimination thresholds, evaluated with the Tacticon, were determined using a two-alternative forced-choice procedure.

RESULTS

Vibratory thresholds increased with decreasing ability to discriminate differences in circumference (P < 0.001) for those below and above 50 years of age. Agreement between the two QST devices was assessed via the kappa-statistic in both age-groups (i.e., < or = 50 years old [kappa = 0.67], > 50 years old [kappa = 0.55]). In multiple logistic regression, where circumference discrimination thresholds were the dependent variable, age, duration of diabetes, and height were found to be independently associated for those > 50 years old.

CONCLUSIONS

The Tacticon offers a simple method of assessing the complex function of area discrimination. Our results suggest that the Tacticon can detect neuropathy in the primary care setting. Its cost, portability, and ease of use provide some advantages over existing QST equipment.

Why does diabetic autonomic neuropathy predict IDDM mortality? An analysis from the Pittsburgh Epidemiology of Diabetes Complications Study

BACKGROUND

Previous studies have suggested that IDDM subjects with diabetic autonomic neuropathy (DAN) have a greatly increased risk of mortality which may relate to a specific cardiologic etiology.

OBJECTIVES

To examine the predictors of DAN in IDDM and its relationship to subsequent mortality.

STUDY POPULATION

The Epidemiology of Diabetes Complications Study based on an incident cohort of childhood onset IDDM subjects. Data from two examinations, separated by 2 years, are utilized.

METHODS

Diabetic autonomic neuropathy was determined by Expiration/Inspiration (E/I ratio). A variety of baseline risk factors were related to its subsequent incidence (n = 57 out of 325 subjects free of DAN at baseline). Two-year mortality by DAN status was also determined for all 479 subjects seen at baseline.

RESULTS

Duration of diabetes, the cardiovascular risk profile (hypertension, elevated LDL cholesterol and triglycerides), and other complications (e.g. nephropathy) were all univariately associated with subsequent DAN (P < 0.01). Smoking status and hemoglobin A1 (HbA1) but less strongly, related (P < 0.05). Cox proportional hazards modeling showed diabetes duration and HbA1 to be significant independent predictors. Distal Symmetrical Polyneuropathy also contributed if added to the model. Mortality was increased four-fold in those with DAN (P = 0.005), although this difference no longer was significant after adjustment for baseline nephropathy (P = 0.35) or hypertension (P = 0.42).

CONCLUSIONS

Duration of diabetes and HbA1 are the major predictors of DAN. However, although DAN is clearly associated with increased mortality, this is largely explained by associations with complications (e.g. nephropathy) and increased cardiovascular risk factors (e.g. hypertension).

Glucose monitoring of patients with diabetes mellitus receiving general anesthesia: a study of the practices of anesthesia providers in a large community hospital

Surgical stress causes hyperglycemia with potential complications (e.g., impaired granulocytic function and delayed wound healing) particularly when glucose levels exceed 250 mg/dL. Standards of care for patients with diabetes undergoing surgery may vary by geographic locale, type of surgical procedure, and type of diabetes. We explored whether anesthesia providers monitor glucose levels in patients with diabetes. Records of 100 patients with diabetes who underwent surgery under general anesthesia (length of procedure: range, 1.9-11.8 hours) were reviewed. Demographic information, glucose levels, frequency of glucose monitoring, and treatment used for diabetes management preoperatively, intraoperatively, and postoperatively were recorded. There were 46 males and 54 females, aged 62 +/- 13 years (55% currently treated with insulin). Of the study cohort, 89% had preoperative, 23% had intraoperative, and 54% had postoperative glucose monitoring performed. As expected, postoperative glucose concentrations were significantly higher than preoperative glucose levels (mean difference, 99 mg/dL, P < .01). The mean postoperative glucose level was 262 +/- 89 mg/dL with 30 of the 54 monitored patients having a postoperative glucose level greater than 250 mg/dL. Individuals treated with insulin and those who underwent major surgery were more likely to have glucose levels monitored. These results suggest that better strategies for monitoring glucose levels during the surgical period are needed.

Little association of lipid parameters and large sensory nerve fiber function in diabetes mellitus

The natural history of diabetic neuropathy and its risk factors are not well understood. The potential association of various lipids [e.g., high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, triglycerides], and lipoprotein(a) [Lp(a)] concentrations, with large sensory nerve fiber function as assessed by vibratory thresholds was examined in a group of 91 individuals with diabetes mellitus. In multivariate analyses, no independent relationships of any of the lipid or lipoprotein parameters measured in this study were found with vibratory thresholds (i.e., dependent variable). Independent associations of age, duration of diabetes, height, and medications that lower blood pressure with vibratory thresholds were shown and explained 51% of the overall variability of the model. In gender-specific models, age, height, and medications that lower blood pressure were statistically significant independent determinates (i.e., males R2 = 0.61, females R2 = 0.39). These cross-sectional data suggest that lipid and lipoprotein parameters measured in this study have little association with large sensory nerve fiber dysfunction. The interesting association with the use of medications that lower blood pressure and vibratory thresholds warrants further investigation.

The progression of retinopathy over 2 years: the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study

This study examined potential risk factors for the incidence and progression of retinopathy in a large representative cohort of childhood onset insulin-dependent diabetic patients. Participants in the Epidemiology of Diabetes Complications (EDC) Study underwent a full clinical examination at baseline and again at a 2-year follow-up. Retinopathy status was ascertained using stereo fundus photographs graded according to the modified Airlie House System. The study population is based on a large cohort of childhood-onset insulin-dependent diabetic patients, seen within 1 year of diagnosis at the Children's Hospital of Pittsburgh between January 1950 and May 1980. A total of 657 subjects participated at baseline (1986-1988), with 80% of eligible survivors taking part in the follow-up examination. This report concerns risk factors associated with the progression of diabetic retinopathy over a 2-year period, and the interaction of these factors with the presence of nephropathy. Analyses showed that baseline diastolic blood pressure was significantly associated with the incidence of any retinopathy, while glycosylated hemoglobin, baseline severity of retinopathy, serum triglycerides, and, to a lesser extent, higher levels of low-density lipoprotein (LDL) cholesterol and fibrinogen were associated with the progression of retinopathy. Progression to proliferative retinopathy was related to higher LDL cholesterol, fibrinogen, serum triglycerides, albumin excretion rate, and glycosylated hemoglobin (GHb). Risk factors varied with the presence of nephropathy. In the absence of nephropathy, GHb was a significant predictor of progression, whilst this was not the case in the presence of nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison between alternative and trade name glucose test strips

OBJECTIVE

To determine the reliability of seven different alternative glucose test strips manufactured for use with three different glucose meters.

RESEARCH DESIGN AND METHODS

Venous blood samples were obtained from volunteers to test trade name glucose test strips on the manufacturers' glucose meters (One Touch II, Glucometer II, and Glucometer III), and the remainder of each sample was used for laboratory determination of blood glucose levels. In addition to the trade name test strips, Quick Check and First Choice test strips were tested on all meters, and Biotel test strips were also tested on the Glucometer III.

RESULTS

In linear regression analysis, the R2 ranged from 0.84 to 0.97 for the test strips compared with plasma glucose values. The test strips with the highest accuracy and precision at all ranges of blood glucose levels were the One Touch II and Glucometer III trade name strips and the Quick Check and First Choice alternative strips for the One Touch II glucose meter and the First Choice alternative strip for the Glucometer II. Subgroup analysis based on ranges of blood glucose values, however, revealed that the alternative strips were not as accurate as the trade name test strips, with the exception of the First Choice alternative test strip for the Glucometer II. All of the trade name test strips were more precise than the alternative test strips designed for the individual meters.

CONCLUSIONS

Alternative glucose test strips can be used to predict the actual laboratory blood glucose values but are generally not as accurate or precise as the trade name test strips.

Use of arterial blood with bedside glucose reflectance meters in an intensive care unit: are they accurate?

OBJECTIVE

To compare blood glucose values obtained from two different sampling sites (arterial catheter and capillary from finger puncture), which were analyzed by a bedside reflectance meter. A sample was also analyzed by standard methods (oxygen electrode oxidation in the laboratory).

DESIGN

Prospective, cross-sectional clinical study.

SETTING

Cardiovascular intensive care unit (ICU) designed for postoperative open-heart surgery patients in a 1,100-bed medical center.

PATIENTS

Sequential sample of 50 patients immediately after open-heart surgery.

MEASUREMENTS AND MAIN RESULTS

The blood glucose concentration of each patient was analyzed on the patient's arrival to the ICU (immediately postoperatively) by three methods: one blood specimen was obtained from an arterial catheter, divided and analyzed either at the bedside by a reflectance meter (glucose method 1) or in the hospital laboratory (glucose method 2); another sample was obtained by lancing the fingertip and the glucose concentration was analyzed at the bedside in the same reflectance meter (glucose method 3). Using paired analyses to compare the mean glucose values of the bedside arterial whole blood sample (method 1) with the arterial serum sample (method 2) demonstrated that the glucose concentration in the arterial whole blood sample (method 1) was significantly (p < .001) higher. For 46 of 50 comparisons, the glucose value in the arterial whole blood sample (method 1) was higher, with a mean difference of 30 mg/dL (1.7 mmol/L). Although the mean difference was reduced to 10 mg/dL (0.6 mmol/L) when the arterial whole blood sample (method 1) was corrected for the hematocrit (i.e., < 35% [< 0.35]), the mean glucose concentration in the arterial whole blood samples (method 1) remained statistically higher (p < .05). The glucose concentration in the arterial serum sample (method 2) was significantly higher than the value determined from the bedside capillary sample (method 3) before (p < .05) and after (p < .001) correction for hematocrit. The difference in mean glucose concentrations between the arterial serum sample (method 2) and bedside capillary sample (method 3) was 9 mg/dL (0.5 mmol/L) when the capillary specimen (method 3) was not corrected for hematocrit. This difference increased to 21 mg/dL (1.2 mmol/L) when low hematocrit values were considered and appropriate adjustments of the glucose values were made. At the bedside, one can accurately correct arterial whole blood glucose values to correspond to laboratory values by the following formula: (0.94 x arterial whole blood glucose) + (4.6 x hematocrit) + (-16.5 x [37 degrees C--patient's temperature])--132 = laboratory glucose value.

CONCLUSIONS

Since arterial whole blood samples give higher glucose results than arterial serum, the use of arterial whole blood in combination with reflectance meters must be recommended with caution. This caution is especially advised if the glucose values obtained with arterial whole blood are used in conjunction with a sliding scale of insulin, which depends on threshold concentrations of glucose. In our hospital, use of arterial whole blood in combination with reflectance meters could have resulted in an incorrect dose of insulin in 31 of 50 patients.

The effects of age and diabetes mellitus on nerve function

OBJECTIVE

This project evaluated the association of age and vibratory thresholds (assessment modality of large sensory nerve fibers) in subjects with and without diabetes mellitus.

DESIGN

Cross-sectional study.

SETTING

Medical Research Institute of Delaware.

PARTICIPANTS

Individuals with non-insulin-dependent diabetes mellitus and non-diabetic control subjects.

MEASUREMENTS

Vibratory thresholds were examined in four age groups (ie, < 45 yrs, 45-54 yrs, 55-64 yrs, > or = 65 yrs). The independent association of age, duration of diabetes, height, gender, glycemic control, and smoking history were analyzed in terms of their relationship to vibratory thresholds.

MAIN RESULTS

Vibratory thresholds increased with age for both control and diabetic subjects. Comparing controls with diabetic subjects in the same age categorizes revealed significant differences for vibratory thresholds only in the > or = 65 year old age group. Modeling with vibratory thresholds as the dependent variable showed that age and male gender were independently associated with vibratory thresholds for the controls and explained the majority of the variability (R2 = 0.79). Age, duration of diabetes, and height were independently associated with vibratory thresholds for the diabetic subjects but explained much less of the variability (R2 = 0.39).

CONCLUSIONS

The results suggest an acceleration of the natural aging process for large sensory nerve fiber function in diabetic subjects. Thus, young diabetic subjects may be at a risk of lower extremity complications as a result of injuries similar to that older non-diabetic individuals.