Glycaemia-independent ethnic differences in HbA(1c) in subjects with impaired glucose tolerance

Abstract

Aim: To study the ethnic differences in HbA(1c) between Whites and South Asians with impaired glucose tolerance.

Methods: We audited 75g oral glucose tolerance tests (OGTT) performed in Clinical Chemistry, New Cross Hospital, Wolverhampton over 1 year. HbA(1c) and glycaemia were compared between Whites and South Asians with impaired glucose intolerance (IGT).

Results: There were 46 South Asians (22 female) and 88 Whites (41 female). South Asian subjects were younger (59.2 +/- 14.31 vs. 67.6 +/- 12.63 yrs; P < 0.001) and weighed less (78.1 +/- 17.2 vs. 87.47 +/- 19.1 kgs; P < 0.001) than White subjects. HbA(1c) levels were higher (6.5 +/- 0.7 vs. 6.1 +/- 0.6%; P < 0.001) in South Asians compared to Whites. Fasting glucose (5.71 +/- 0.5 vs. 5.93 +/- 0.7; P = 0.039) was lower in South Asians but 2hour glucose (10.5 +/- 1.0 vs. 10.40 +/- 0.9; P = 0.404) was similar in both ethnic groups.

Conclusion: South Asians have higher HbA(1c) levels than Whites despite lower fasting glucose value on OGTT, indicating ethnic differences in HbA(1c) are due to glycaemia-independent factors.