Higher fasting insulin but lower fasting C‐peptide levels in African Americans in the US population

Harris, Maureen I.; Cowie, Catherine C.; Gu, Ken; Francis, Mildred E.; Flegal, Katherine M.; Eberhardt, Mark S.

doi:10.1002/dmrr.273

Cited by 46 publications

(37 citation statements)

References 26 publications

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“…Subjects had impaired fasting glucose (109 ± 6 mg dL −1 ) and fasting insulin values (9.8 ± 4.5 µU mL −1 ) in the normal range for this age-group (25). Resting systolic (130 ± 17 mmHg) and diastolic (81 ± 6 mmHg) blood pressures were also in the normal range for older people.…”

Section: Resultsmentioning

confidence: 95%

Three 15-min Bouts of Moderate Postmeal Walking Significantly Improves 24-h Glycemic Control in Older People at Risk for Impaired Glucose Tolerance

et al. 2013

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OBJECTIVEThe purpose of this study was to compare the effectiveness of three 15-min bouts of postmeal walking with 45 min of sustained walking on 24-h glycemic control in older persons at risk for glucose intolerance.RESEARCH DESIGN AND METHODSInactive older (≥60 years of age) participants (N = 10) were recruited from the community and were nonsmoking, with a BMI <35 kg/m2 and a fasting blood glucose concentration between 105 and 125 mg dL−1. Participants completed three randomly ordered exercise protocols spaced 4 weeks apart. Each protocol comprised a 48-h stay in a whole-room calorimeter, with the first day serving as the control day. On the second day, participants engaged in either 1) postmeal walking for 15 min or 45 min of sustained walking performed at 2) 10:30 a.m. or 3) 4:30 p.m. All walking was on a treadmill at an absolute intensity of 3 METs. Interstitial glucose concentrations were determined over 48 h with a continuous glucose monitor. Substrate utilization was measured continuously by respiratory exchange (VCO2/VO2).RESULTSBoth sustained morning walking (127 ± 23 vs. 118 ± 14 mg dL−1) and postmeal walking (129 ± 24 vs. 116 ± 13 mg dL−1) significantly improved 24-h glycemic control relative to the control day (P < 0.05). Moreover, postmeal walking was significantly (P < 0.01) more effective than 45 min of sustained morning or afternoon walking in lowering 3-h postdinner glucose between the control and experimental day.CONCLUSIONSShort, intermittent bouts of postmeal walking appear to be an effective way to control postprandial hyperglycemia in older people.

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Section: Resultsmentioning

confidence: 95%

Three 15-min Bouts of Moderate Postmeal Walking Significantly Improves 24-h Glycemic Control in Older People at Risk for Impaired Glucose Tolerance

et al. 2013

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“…Both measures of dynamic insulin secretion as well as the DI were also noted to be greater in African Americans than European Americans (Table 1, Fig. 1D), perhaps due to decreased insulin clearance in African Americans [25, 26]. Overall, our study shows that persons identified as having “prediabetes” based on HbA1c values of 5.7-6.4% show no evidence of defective insulin action or secretion, compared with persons of lower or “normal” HbA1c status.…”

Section: Discussionmentioning

confidence: 99%

Glucoregulatory function among African Americans and European Americans with normal or pre-diabetic hemoglobin A1c levels

et al. 2014

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Objective A hemoglobin (Hb) A1c range of 5.7%-6.4% has been recommended for the diagnosis of prediabetes. To determine the significance of such “prediabetic” HbA1c levels, we compared glucoregulatory function in persons with HbA1c levels of 5.7%-6.4% and those with HbA1c < 5.7%. Methods We studied 280 nondiabetic adults (142 black, 138 white; mean (± SD) age 44.2 ± 10.6 y). Each subject underwent clinical assessment, blood sampling for HbA1c measurement, and a 75-g oral glucose tolerance test at baseline. Additional assessments during subsequent outpatient visits included insulin sensitivity, using homeostasis model assessment (HOMA)-IR and the hyperinsulinemic euglycemic clamp; insulin secretion, using HOMA-B and frequently samples intravenous glucose tolerance test (FSIVGTT) and disposition index (DI); and measurement of fat mass, using DXA. Results Compared to subjects with HbA1c < 5.7%, persons with HbA1c levels of 5.7%-6.4% were older, and had higher body mass index (BMI) and insulin secretion but similar insulin sensitivity. When the two groups were matched in age and BMI, persons with HbA1c 5.7–6.4% were indistinguishable from those with HbA1c <5.7% with regard to all measures of glycemia glucoregulatory function. Conclusions Unlike glucose-defined prediabetes status, an HbA1c range of 5.7%- 6.4% does not reliably identify individuals with impaired insulin action or secretion, the classical defects underlying the pathophysiology of prediabetes. Thus, HbA1c cannot validly replace blood glucose measurement in the diagnosis of prediabetes. If utilized as a screening test due to convenience, aberrant HbA1c values should be corroborated with blood glucose measurement before therapeutic intervention.

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“…Data from the third National Health and Nutrition Examination Survey show that, among men without diabetes, fasting insulin is highest in Mexican Americans compared to African Americans and whites, and among women without diabetes, both African Americans and Mexican Americans have higher fasting insulin levels than whites (Harris et al 2002). The differences for C-peptide are similar, but black men and women have lower levels of C-peptide, suggesting a defect in insulin clearance that is different than in whites and Hispanics.…”

Section: Disparities In Adult Cardiovascular Health and Their Implicamentioning

confidence: 96%

Lifecourse Social Conditions and Racial and Ethnic Patterns of Cognitive Aging

2008

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A lifecourse perspective is key for understanding and interpreting racial and ethnic patterns in neuropsychological test performance. In this article, we discuss contextual factors that shape the environmental conditions encountered by racial and ethnic minorities in the United States, in particular African-Americans. These conditions include geographic segregation at the level of regions, metropolitan areas, and neighborhoods; intra- and inter-national migration patterns; socioeconomic position, including financial resources, and occupational and educational opportunities; discrimination; and group resources. Each of these exposures sets in course a cascade of individual mediators that ultimately manifest in neuropsychological outcomes. The physiological and behavioral consequences of these pathways likely accumulate across the lifecourse. We focus on cognitive aging, although the processes discussed here begin in infancy and likely influence cognitive outcomes throughout life from childhood into old age. A lifecourse framework can help inform clinical encounters, neuropsychological research, and surveillance regarding the population prevalence of cognitive impairments.

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Higher fasting insulin but lower fasting C‐peptide levels in African Americans in the US population

Cited by 46 publications

References 26 publications

Three 15-min Bouts of Moderate Postmeal Walking Significantly Improves 24-h Glycemic Control in Older People at Risk for Impaired Glucose Tolerance

Three 15-min Bouts of Moderate Postmeal Walking Significantly Improves 24-h Glycemic Control in Older People at Risk for Impaired Glucose Tolerance

Glucoregulatory function among African Americans and European Americans with normal or pre-diabetic hemoglobin A1c levels

Lifecourse Social Conditions and Racial and Ethnic Patterns of Cognitive Aging

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