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Biomedical subjects

Randie R Little

Publications and source records attributed to Randie R Little.

16 recordsLinked to original sources
PubMed2006

Trends in hyperinsulinemia among nondiabetic adults in the U.S.

OBJECTIVE: Insulin resistance and compensatory hyperinsulinemia have been proposed as increasing risk for a variety of abnormalities and clinical syndromes, including type 2 diabetes and cardiovascular disease. Our aim was to assess the trends in the mean concentrations of fasting serum insulin and the prevalence of hyperinsulinemia among nondiabetic adults during the periods of 1988-1994 and 1999-2002 in the U.S. RESEARCH DESIGN AND METHODS: We conducted analyses of data among men and nonpregnant women without diabetes aged >/=20 years from the Third National Health and Nutrition Examination Survey (NHANES III; 1988-1994; n = 7,926) and NHANES 1999-2002 (n = 2,993). Both surveys were designed to represent the noninstitutionalized civilian U.S. population. We calculated age-adjusted mean concentrations of fasting insulin and the prevalence of hyperinsulinemia defined using the 75th percentile of fasting insulin among nondiabetic individuals as the cutoff value. RESULTS: The geometric mean concentrations of fasting insulin increased by approximately 5% from 1988-1994 to 1999-2002 among nondiabetic adults aged >/=20 years in the U.S. Mexican-American men, men and women aged 20-39 years, and non-Hispanic white women had a greater relative increase in the mean concentrations of fasting insulin than their counterparts. The prevalence of hyperinsulinemia increased by 35.1% overall (38.3% among men and 32.1% among women). CONCLUSIONS: In parallel with the obesity epidemic, concentrations of fasting insulin and prevalence of hyperinsulinemia have increased remarkably among nondiabetic U.S. adults.

Adult↗
PubMed2004

Effects of beta thalassemia minor on results of six glycated hemoglobin methods.

BACKGROUND: Beta-thalassemia minor (BTM) is a common benign condition that can be present in patients with diabetes mellitus. There are conflicting reports about the effect of BTM on glycated hemoglobin (gHb) measurements. We evaluated 6 gHb methods using samples from non-diabetic subjects with BTM. METHODS: Samples submitted for hemoglobin phenotype analysis were evaluated. A total of 57 samples (30 controls and 27 with BTM) from non-diabetic subjects were selected. GHb analysis was performed by Tosoh A1c 2.2+, Primus CLC 330, Bayer DCA 2000, Beckman Coulter, Synchron CX7 and LX20, and Roche Tina-quant II assays. RESULTS: The A1c 2.2+, CLC 330, DCA 2000 and Tina-quant II assays showed no statistically significant difference between the control and BTM groups. In contrast, BTM results were significantly higher than controls on the Synchron CX7 analyzer and borderline significant on the Synchron LX20 (p=0.051). Further investigation demonstrated an increase in Synchron %HbA(1c) results with decreasing hemoglobin concentrations. CONCLUSIONS: In this study using samples from subjects with normal or near-normal gHb, BTM does not affect gHb measurements per se. However, the Synchron methods yielded higher results for samples with lower hemoglobin concentrations, like those that can be seen in BTM. The Synchron method was improved at the end of 2003, which minimized this problem.

Adult↗
PubMed2003

Testing for microalbuminuria in 2002: barriers to implementing current guidelines.

BACKGROUND: Testing for microalbuminuria is recommended to detect early kidney damage in patients with diabetes or other diseases. However, few studies have examined laboratory practices for microalbuminuria testing in the general community. METHODS: In 2002, all laboratories in Montana and reference laboratories used by Montana laboratories for microalbuminuria measurement were surveyed by mail to ascertain if they provided testing for microalbuminuria, specific tests performed, and units and cutoff values used to report microalbuminuria results. RESULTS: One hundred three of 126 laboratories (82%) responded to the survey. Overall, 79% of laboratories offered quantitative testing for microalbuminuria, either on site or through a reference laboratory. Twenty-five laboratories (24%) surveyed provided quantitative testing for microalbuminuria on site. Only 14 of 23 laboratories offering albumin-creatinine ratios on site reported results in units and cutoff values consistent with current recommendations. Fewer laboratories provided 24-hour (6 of 17 laboratories) or other timed (2 of 7 laboratories) testing, and many of these laboratories did not report results using recommended units and cutoff values. Overall, only 11 of 25 laboratories (44%) with on-site testing reported microalbuminuria values from 1 or more types of specimens exclusively using recommended units and cutoff values. CONCLUSION: Quantitative testing for microalbuminuria is not offered universally, and results often are reported in units and cutoff values that differ from current clinical recommendations.

Albuminuria↗
PubMed2003

Glycated hemoglobin standardization--National Glycohemoglobin Standardization Program (NGSP) perspective.

The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by glycated hemoglobin (GHb). Many diabetes organizations worldwide now recommend GHb targets in terms of DCCT/ UKPDS hemoglobin A1c (HbA1c). However, in 1993 there was a lack of comparability of GHb test results among methods and laboratories that represented a major obstacle to meaningful implementation of specific guidelines for diabetes care. The National Glycohemoglobin Standardization Program (NGSP) was implemented to enable laboratories to report DCCT/UKPDS-traceable GHb/HbA1c results. The number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. Proficiency testing results show marked improvement in the comparability of GHb results. By the end of 2002, 98% of surveyed laboratories (n = approx. 2000) reported GHb results as HbA1c or equivalent compared to 50% in 1993. Ninety-seven percent of laboratories used an NGSP-certified method. For most certified methods in 2002, between-laboratory CVs were < 5%. For all certified methods in 2002, the mean HbA1c value (%) was within 0.8% HbA1c from the NGSP target at all HbA1c concentrations. The vast majority of laboratories in the US are now reporting results that are traceable to DCCT/UKPDS outcomes.

Certification↗
PubMed2002

Defining the relationship between plasma glucose and HbA(1c): analysis of glucose profiles and HbA(1c) in the Diabetes Control and Complications Trial.

OBJECTIVE: To define the relationship between HbA(1c) and plasma glucose (PG) levels in patients with type 1 diabetes using data from the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS: The DCCT was a multicenter, randomized clinical trial designed to compare intensive and conventional therapies and their relative effects on the development and progression of diabetic complications in patients with type 1 diabetes. Quarterly HbA(1c) and corresponding seven-point capillary blood glucose profiles (premeal, postmeal, and bedtime) obtained in the DCCT were analyzed to define the relationship between HbA(1c) and PG. Only data from complete profiles with corresponding HbA(1c) were used (n = 26,056). Of the 1,441 subjects who participated in the study, 2 were excluded due to missing data. Mean plasma glucose (MPG) was estimated by multiplying capillary blood glucose by 1.11. Linear regression analysis weighted by the number of observations per subject was used to correlate MPG and HbA(1c). RESULTS: Linear regression analysis, using MPG and HbA(1c) summarized by patient (n = 1,439), produced a relationship of MPG (mmol/l) = (1.98 . HbA(1c)) - 4.29 or MPG (mg/dl) = (35.6 . HbA(1c)) - 77.3, r = 0.82). Among individual time points, afternoon and evening PG (postlunch, predinner, postdinner, and bedtime) showed higher correlations with HbA(1c) than the morning time points (prebreakfast, postbreakfast, and prelunch). CONCLUSIONS: We have defined the relationship between HbA(1c) and PG as assessed in the DCCT. Knowing this relationship can help patients with diabetes and their healthcare providers set day-to-day targets for PG to achieve specific HbA(1c) goals.

Blood Glucose↗
PubMedDate not supplied

Determination of glycated hemoglobin in clinically silent hemoglobin variants.

BACKGROUND: Evaluation of glycated hemoglobin determination methods in patients with clinically silent hemoglobin variants. METHODS: HbA1c results were determined with various methods, including a new enzymatic assay, a boronate affinity HPLC, immunoassays and ion-exchange HPLC in patients with the clinically silent hemoglobin variants Hb Graz, Hb Sherwood Forest, Hb D and Hb O Padova. RESULTS: The effect of hemoglobin variants on glycated hemoglobin determination was method-dependent. The enzymatic and boronate affinity HPLC method did not interfere with any of the variants evaluated. In contrast, Hb Graz interfered with all immunoassay and ion-exchange HPLC methods evaluated. The Tosoh ion-exchange HPLC method HLC-723 did not detect the late migrating Hb O Padova in the chromatogram, but this hemoglobin variant still interfered causing artificially low HbA1c results. CONCLUSIONS: Our study underscores the need for clinical laboratories and physicians to be aware of the limitations of their HbA1c assay methods as well as the importance of visual inspection of ion-exchange chromatograms to detect abnormalities caused by the hemoglobin variants. Samples with clinically silent Hb variants should be analyzed by a second method with a different assay principle, preferably a boronate affinity HPLC or an enzymatic assay.

Boronic Acids↗