Diagnostic accuracy of glycated hemoglobin for gestational diabetes mellitus: a systematic review and meta-analysis.

Background We conducted a systematic review and meta-analysis to establish the overall accuracy of glycated hemoglobin (HbA1c) in the diagnosis of gestational diabetes mellitus (GDM) diagnosis. Methods We searched MEDLINE, EMBASE, SCOPUS and ClinicalTrials.gov up to October 2018, using keywords related to GDM, HbA1c and diagnosis. Studies were included that were carried out with pregnant women without previous diabetes that assessed the performance of HbA1c (index test) compared to the 75 g oral glucose tolerance test (OGTT) (reference test) for the diagnosis of GDM, that measured HbA1c by standardized methods and presented data necessary for drawing 2 × 2 tables. Results This meta-analysis included eight studies, totaling 6406 pregnant women, of those 1044 had GDM. The diagnostic accuracy of HbA1c was reported at different thresholds ranging from 5.4% (36 mmol/mol) to 6.0% (42 mmol/mol), and the area under the curve (AUC) was 0.825 (95% confidence interval [CI] 0.751-0.899), indicating a good level of overall accuracy. The pooled sensitivities and specificities were 50.3% (95% CI 24.8%-75.7%) and 83.7% (67.5%-92.7%); 24.7% (10.3%-48.5%) and 95.5% (85.7%-98.7%); 10.8% (5.7%-19.41%) and 98.7% (96.2%-99.5%); 12.9% (5.5%-27.5%) and 98.7% (97.6%-99.3%), for the cut-offs of 5.4% (36 mmol/mol), 5.7% (39 mmol/mol), 5.8% (40 mmol/mol) and 6.0% (42 mmol/mol), respectively. Conclusions We observed a high heterogeneity among the studies. The effect of ethnicities, different criteria for OGTT interpretation and the individual performance of HbA1c methods may have contributed to this heterogeneity. The HbA1c test presents high specificity but low sensitivity regardless of the threshold used to diagnose GDM. These findings point to the usefulness of HbA1c as a rule-in test. HbA1c should be used in association with other standard diagnostic tests for GDM diagnosis.

Serum vitamin D insufficiency is related to blood pressure in diabetic pregnancy.

BACKGROUND: Vitamin D deficiency in pregnancy has been associated with an increased risk of preeclampsia. However, the association between serum vitamin D and blood pressure in pregnant women has been scarcely evaluated, particularly in women with a high risk of developing hypertensive disorders of pregnancy. We sought to evaluate the association between serum 25-hydroxyvitamin D and blood pressure in pregnant women with gestational diabetes mellitus (GDM). METHODS: A cohort of 184 pregnant women with GDM was followed during the third trimester of pregnancy and early puerperium. Blood pressure was recorded in all prenatal visits, and serum vitamin D was measured by chemiluminescence immunoassay. Pearson's coefficients and multiple linear regressions were used to study predictors of blood pressure levels. RESULTS: Women with vitamin D insufficiency (<30ng/mL; n = 159) had higher systolic and diastolic blood pressure than the remaining participants. In white women (n = 136), serum vitamin D levels presented a significant negative correlation with systolic blood pressure at the beginning (r = -0.268; P = 0.002) and at the end of the third trimester (r = -0.203; P = 0.02), and vitamin D significantly affected systolic blood pressure after adjusting for confounders. This was not observed in women of other ethnicities. CONCLUSIONS: In this cohort of pregnant women with GDM, vitamin D insufficiency was associated with higher blood pressure, and in white women, serum vitamin D was an independent predictor of systolic blood pressure during pregnancy.

The effect of aspirin and vitamins C and E on HbA1c assays.

BACKGROUND: Aspirin (ASA) and vitamins C and E may inhibit non-enzymatic glycation in vivo and may also interfere with HbA(1c) assays, masking true results. We investigated the effect of usual doses of ASA, vitamin C and E on HbA1c levels in a group of non-diabetic volunteers. METHODS: A randomized clinical trial was performed with 28 healthy non-diabetic individuals. Subjects were allocated to take ASA 200 mg/day, vitamin C 1 g/day, vitamin E 400 mg/day, or to a control group, for a period of 4 months. Blood samples were collected at baseline and at monthly intervals for HbA1c analysis by HPLC Variant II (BioRad), HPLC L-9100 (Merck - Hitachi) and Tina Quant HbA(1c) II immunoassay (Roche). RESULTS: HbA(1c) levels of the control, vitamin C and E groups did not change throughout the study, independently of the method used. HbA(1c) measured by Hitachi L-9100 HPLC increased significantly (P=0.033) at 4 months after ASA intake, although this increase was of only 0.17%. CONCLUSIONS: Treatment with vitamins C and E in pharmacological doses does not have any impact on HbA1c measurements in non-diabetic patients with the three methods employed. ASA induces a modest, not clinically relevant, increase in HbA1c levels with one of the methods.

Effect of pre-analytical variables on glycohemoglobin measurements in routine clinical care.

OBJECTIVES: To analyze the contribution of the labile A1C fraction (L-A1C) and sample storage conditions on GHb measurements. DESIGN AND METHODS: L-A1C separation (HPLC Hitachi L-9100) was evaluated before and after sample treatment by four different methods for L-A1C removal. Different sample storage conditions were analyzed. RESULTS: L-A1C may overestimate up to 1.64% total A1C if not properly separated. Samples were stable for up to 10, <1, and at least 100 days for whole blood stored at 4, -20, and -80 degrees C, respectively. CONCLUSIONS: The presence of L-A1C may overestimate GHb results. Samples may be kept under refrigeration up to 10 days and at -80 degrees C if long-term storage is required.

Fatty acid composition of serum lipid fractions in type 2 diabetic patients with microalbuminuria.

OBJECTIVE: To determine the fatty acid composition of serum phospholipid, triglyceride, and cholesterol ester fractions and to analyze the lipid profile of microalbuminuric type 2 diabetic patients. RESEARCH DESIGN AND METHODS: A case-control study was conducted with 72 patients: 37 were normoalbuminuric (urinary albumin excretion rate [UAER] <20 microg/min), and 35 were microalbuminuric (UAER 20-200 microg/min). After 4 weeks of a standardized diet, the fatty acid composition of phospholipid, triglyceride, and cholesterol ester fractions was determined by gas chromatography. Total cholesterol and triglycerides were measured by enzymatic-colorimetric methods; cholesterol HDL by double precipitation with heparin, MnCl(2), and dextran sulfate; and apolipoprotein B by immunoturbidimetry. RESULTS: Microalbuminuric patients showed a lower proportion of polyunsaturated fatty acids (24.8 +/- 11.0%), especially of the n-6 family (21.7 +/- 10.5%), in triglyceride fraction than normoalbuminuric patients (34.1 +/- 11.3%, P = 0.001 and 31.4 +/- 11.5%, P < 0.001, respectively). Patients with microalbuminuria also presented higher levels of saturated fatty acids in triglyceride fraction (43.4 +/- 18.0% vs. 34.7 +/- 13.1%, P = 0.022). In the logistic regression analysis, only the proportion of polyunsaturated fatty acids in triglyceride fraction remained significantly associated with microalbuminuria (odds ratio [OR] 0.92, 95% CI 0.85-0.98, P = 0.019). Total cholesterol, HDL cholesterol, triglyceride, and apolipoprotein B levels were similar in normo- and microalbuminuric patients. CONCLUSION: Microalbuminuria in type 2 diabetic patients is associated with low polyunsaturated fatty acid contents in serum triglyceride fraction. This association may represent a risk factor for cardiovascular disease and may contribute to the progression of renal disease.

Diabetes melito: diagnóstico, classificaçäo e avaliaçäo do controle glicêmico / Diabetes mellitus: diagnosis, classification and glucose control evaluation

Diabetes e alteraçöes da tolerância à glicose säo freqüentes na populaçäo adulta e estäo associados a um aumento da mortalidade por doença cardiovascular e complicaçöes microvasculares. O diagnóstico destas situaçöes deve ser feito precocemente, utilizando métodos sensíveis e acurados, já que mudanças no estilo de vida e a correçäo da hiperglicemia podem retardar o aparecimento do diabetes ou de suas complicaçöes. O teste oral de tolerância à glicose é o método de referência, considerando-se a presença de diabetes ou tolerância à glicose diminuída quando a glicose plasmática de 2h após a ingestäo de 75g de glicose for >/= 200mg/dl ou >/= 140 e <200mg/dl, respectivamente. Quando este teste näo puder ser realizado, utiliza-se a medida da glicose piasmática em jejum, considerando-se como diabetes ou glicose alterada em jejum quando os valores forem >/= 126mg/dl ou >/= 110 e <126mg/dl, respectivamente. A medida,da glico-hemoglobina näo deve ser utilizada para o diagnóstico, mas é o método de referência para avaliar o grau de controle glicémico a longo prazo. A classificaçäo etiológica proposta atualmente para o diabetes melito inclui 4 categorias: diabetes melito tipo 1, diabetes melito tipo 2, outros tipos específicos de diabetes e diabetes gestacional. A classificaçäo do paciente é usualmente feita em bases clínicas, mas a medida de auto-anticorpos e do peptídeo C pode ser útil em alguns casos.

Efeito do sexo e da gestacao sobre os niveis sericos de frutosamina de individuos normais / Effect of sex gender and pregnancy on frutosamine serum levels in normal individuals

A frutosamina e um indice do controle metabolico no diabete melito, refletindo as variacoes da glicemia nas ultimas 2-3 semanas. Representa um conjunto de proteinas glicosadas, cuja fracao principal e a albumina. Com o objetivo de esclarecer os valores normais da frutosamina em homens, mulheres e gestantes, os niveis sericos de frutosamina foram medidos em 42 individuos normais(homens, n=21, idades 24-81 anos; mulheres, n=21, idades 22-71 anos) e 36 gestantes (idades 18-38 anos, idade gestacional 17-37 semanas). A frutosamina foi medida pelo metodo colorimetrico em um analisador automatico COBAS MIRA-ROCHE. Os valores de frutosamina(media +- desvio padrao) observados em homens (2,99 +- 0,32 mmol/l) foram maiores do que nas mulheres (2,70 +- 0,26 mmol/l). Os valores normais das gestantes foram menores (2,40 +- 0,22 mmol/l) do que nas mulheres nao-gravidas e a correcao da frutosamina de acordo com os niveis de albumina serica nao modificaram os resultdos. Os dados apresentados indicam que devem ser considerados o sexo e a presenca ou nao de gravidez para se definir os limites normais dos valores de frutosamina serica