Effect of ethnicity on HbA1c levels in individuals without diabetes: Systematic review and meta-analysis

Abstract

Aims/HypothesisDisparities in HbA1c levels have been observed among ethnic groups. Most studies were performed in patients with diabetes mellitus (DM), which may interfere with results due to the high variability of glucose levels. We conducted a systematic review and meta-analysis to investigate the effect of ethnicity on HbA1c levels in individuals without DM.MethodsThis is a systematic review with meta-analysis. We searched MEDLINE and EMBASE up to September 2016. Studies published after 1996, performed in adults without DM, reporting HbA1c results measured by certified/standardized methods were included. A random effects model was used and the effect size was presented as weighted HbA1c mean difference (95% CI) between different ethnicities as compared to White ethnicity.ResultsTwelve studies met the inclusion criteria, totalling data from 49,238 individuals. There were significant differences between HbA1c levels in Blacks [0.26% (2.8 mmol/mol); 95% CI 0.18 to 0.33 (2.0 to 3.6), p <0.001; I2 = 90%, p <0.001], Asians [0.24% (2.6 mmol/mol); 95% CI 0.16 to 0.33 (1.7 to 3.6), p <0.001; I2 = 80%, p = 0.0006] and Latinos [0.08% (0.9 mmol/mol); IC 95% 0.06 to 0.10 (0.7 to 1.1); p <0.001; I2 = 0%; p = 0.72] when compared to Whites.Conclusions/InterpretationThis meta-analysis shows that, in individuals without DM, HbA1c values are higher in Blacks, Asians, and Latinos when compared to White persons. Although small, these differences might have impact on the use of a sole HbA1c point to diagnose DM in all ethnic populations.

Impact of mismatches in HbA1c vs glucose values on the diagnostic classification of diabetes and prediabetes

“…In the present study, higher mismatch tertile groups included progressively higher proportions of black participants, as well as higher proportions of men, older participants and participants with higher BMIs. Our findings are similar to those of other studies, including those in cohorts without diabetes, showing increased HbA 1c levels with older age [15] and with black race [14,16,17], but differs from the ACCORD study findings [3], where the higher mismatch tertiles (based on HbA 1c vs fasting glucose levels) included a higher proportion of black participants, but had distributions of sex, age and BMI similar to those of the lowest tertile. Our findings were similar when average glucose was defined according to the OGTT fasting glucose value, or the mean of the OGTT fasting glucose and OGTT 2-h glucose values, or the mean of the two OGTT measurements plus the GCT 1-h glucose value.…”

Definition, Classification and Diagnosis of Diabetes, Prediabetes and Metabolic Syndrome

“…Studies also show the relationship between glucose levels and A1C varies between people living at extremes of altitude (34). In addition, studies of various ethnicities indicate that African Americans, American Indians, Hispanics and Asians have A1C values that are up to 0.4% higher than those of non-Hispanic white individuals at similar levels of glycemia (35)(36)(37)(38), suggesting people from these ethnic groups would have a higher chance of being diagnosed with diabetes by current A1C criteria. Research is required to determine if A1C levels differ in Canadians of African descent or Indigenous peoples.…”

HbA1c: a review of non-glycaemic variables

“…A meta-analysis of non-diabetic participants demonstrated statistically significantly higher levels of HbA1c in black (2.8 mmol/mol, 95% CI 0.18 to 0.33), Asian (2.6 mmol/mol, 95% CI 0.16 to 0.33) and Latino cohorts (0.9 mmol/mol, 95% CI 0.06 to 0.10) compared with Caucasian 45. In a prospective study using continuous glucose monitoring and comparing 104 black and 104 white patients with known T1DM over 12 weeks, black patients had on average an HbA1c higher by 0.4% than whites for comparable average glucose measures 46.…”