How to minimize missing those subjects with high 2HR plasma glucose but 'normal' fasting plasma glucose levels?

Among the subjects with 'normal' fasting plasma glucose (PG) levels (< 7.0 mmol/L), some of them are actually suffering from impaired glucose tolerance and diabetes, which can only be diagnosed by 2hr PG levels. We aim to find out a proper clinical approach in order to minimize missing those subjects with high 2hr PG but 'normal' fasting PG levels. We analyzed data collected from a previously published population-based prevalence survey for glucose intolerance in 1486 Hong Kong Chinese subjects who had no past history of diabetes. Of the 1468 subjects, there were 138 subjects (9.4%) having "missed glucose intolerance". Compared to the diabetic subjects (fasting plasma glucose > or = 7.0 mmol/L) after adjustment for age, the subjects with missed glucose intolerance had similar characteristics except lower glycemic level. Compared to the normal subjects (fasting plasma glucose < 7.0 mmol/L) after adjustment for age, subjects with missed glucose intolerance had more obesity (both general and central), more hypertension, worse glycemic status and lipid profile in both men and women. There were 38 subjects (2.6%) having impaired fasting glucose. Of these 38 subjects, 24 (63.2%) had missed glucose intolerance. The detection of missed glucose intolerance increased from 9.7% of overall male subjects to 23.1% in men with hypertension to 52.9% in men with both hypertension and family history of diabetes. Similarly, the detection of missed glucose intolerance increased from 9.0% of overall female subjects to 25.7% in women with obesity to 45.2% in women with both obesity and hypertension. If only fasting plasma glucose is performed, 4% of subjects will be diagnosed to have diabetes or impaired fasting glucose while up to 10% of subjects having impaired glucose tolerance or diabetes will be missed in Hong Kong Chinese. The latter 2 groups of subjects have similar cardiovascular risk factors to those with fasting PG > or = 7.0 mmol/L. We recommend that for those with a family history of diabetes, hypertension or obesity, an oral glucose tolerance test instead of fasting plasma glucose should be used in the first place for the diagnosis of glucose intolerance. For those with impaired fasting glucose, a routine follow-up oral glucose tolerance test should also be performed. This clinical approach may improve the detection of those subjects with glucose intolerance, who will be otherwise missed by using fasting plasma glucose alone.