Evaluation of glycaemic status in young people with clinical insulin resistance; fasting glucose, fasting insulin or an oral glucose tolerance test?
OBJECTIVE
It is important to identify young people with prediabetes for early intervention. However, it is unclear how to best screen overweight and obese young people for prediabetes. The objective of this study was to compare fasting indices with an oral glucose tolerance test (OGTT) in diagnosing prediabetes.


METHODS
Retrospective review.


METHODS
A total of 224 young people, aged 12.0 years (range: 3.2-17.3 years), with clinical features of insulin resistance, who had an OGTT between 2000 and 2007 at a tertiary children's hospital, Sydney, Australia.


METHODS
Oral glucose tolerance test.


RESULTS
A total of 168 (75%) participants had normal glucose tolerance, 45 (20%) had prediabetes and 11 (5%) had type 2 diabetes; 29 of those with prediabetes and 10 with type 2 diabetes were identified by fasting glucose criteria alone. Young people with normal fasting glucose and fasting insulin < or =180 pmol/l had lower insulin resistance (homeostasis model assessment median 1.9 vs. 4.2, P < 0.001), higher insulin sensitivity index (2.4 vs. 1.0, P < 0.001) and a lower early insulin response (insulinogenic index 2.5 vs. 4.1, P < 0.001) compared to those with normal fasting glucose and higher fasting insulin levels. If a fasting insulin cut point (< or =180 pmol/l) was used in addition to fasting glucose to determine the need for an OGTT, 114 (68%) young people with normal glucose tolerance would have avoided the test. By contrast, the diagnosis of impaired glucose tolerance, identified by an OGTT, would have been missed in three children.


CONCLUSIONS
Fasting glucose and insulin levels should be measured in young people with insulin resistance before undertaking a time- and resource-intensive OGTT.
Garnett
Sarah P
SP
Division of Research, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia. sarahg@chw.edu.au
Srinivasan
Shubha
S
Birt
Stewart G
SG
Ambler
Geoffrey R
GR
Lawrie
Elizabeth A
EA
Cowell
Chris T
CT
Craig
Maria E
ME
D000293:Adolescent; D001786:Blood Glucose / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance / Q000175:diagnosis*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D009765:Obesity / Q000150:complications; D011236:Prediabetic State / Q000175:diagnosis*; D012189:Retrospective Studies; D012306:Risk
D001786:Blood Glucose; D007328:Insulin