Differences in height explain gender differences in the response to the oral glucose tolerance test— the AusDiab study

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Abstract
Aim To determine the extent of gender‐related differences in the prevalence of glucose intolerance for the Australian population and whether body size may explain such differences. Methods Cross‐sectional data were collected from a national cohort of 11 247 Australians aged ≥ 25 years. Glucose tolerance status was assessed according to both fasting plasma glucose (FPG) and 2‐h plasma glucose (2hPG) levels following a 75‐g oral glucose tolerance test (OGTT). Anthropometric and glycated haemoglobin measurements were also made. Results Undiagnosed diabetes and non‐diabetic glucose abnormalities were more prevalent among men than women when based only on the FPG results (diabetes: men 2.2%, women 1.6%, P = 0.02; impaired fasting glycaemia: men 12.3%, women 6.6%, P < 0.001). In contrast 16.0% of women and 13.0% of men had a 2hPG abnormality (either diabetes or impaired glucose tolerance, P = 0.14). Women had a mean FPG 0.3 mmol/l lower than men (P < 0.001), but 2hPG 0.3 mmol/l higher (P = 0.002) and FPG‐2hPG increment 0.5 mmol/l greater (P < 0.001). The gender difference in mean 2hPG and FPG‐2hPG increment disappeared following adjustment for height. For both genders, those in the shortest height quartile had 2hPG levels 0.5 mmol/l higher than the tallest quartile, but height showed almost no relationship with the FPG. Conclusions Men and women had different glycaemic profiles; women had higher mean 2hPG levels, despite lower fasting levels. It appeared that the higher 2hPG levels for women related to lesser height and may be a consequence of using a fixed glucose load in the OGTT, irrespective of body size.