eMJA: Impact of changing the criteria for diagnosing diabetes in Australia

Letters

Impact of changing the criteria for diagnosing diabetes in Australia

Julie A Pasco, Mark A Kotowicz, Margaret J Henry and Geoffrey C Nicholson

MJA 2002; 176 (7): 353-354

To the Editor: Both the American Diabetes Association (ADA)1 and the World Health Organization (WHO)2 have lowered the fasting plasma glucose (FPG) level for the diagnosis of diabetes from 7.8 mmol/L to 7.0 mmol/L. The Australian Diabetes Society (ADS) has also adopted the lower level.3 However, these organisations differ in the procedure for diagnosis they recommend. The recent article by Hilton and colleagues4 compared these procedures, with particular attention to including an oral glucose tolerance test (OGTT). We, on the other hand, have investigated the impact of lowering the diagnostic FPG level to 7.0 mmol/L.

Data were obtained by the Geelong Osteoporosis Study from an age-stratified sample of women randomly selected from electoral rolls for the Barwon Statistical Division5 and adjusted to match the national age profile. Venous FPG level was determined after an overnight fast, together with blood pressure (BP, seated) and anthropometric measurements, in 944 women aged 20–91 years (mean age, 47.5 years; SD, 17.8 years). History of diabetes was ascertained by questionnaire.

The prevalence of self-reported diabetes and diabetes defined by an FPG level of 7.0 mmol/L or higher was 4.3% (95% CI, 3.0%–5.6%; 41 women), whereas using an FPG level of 7.8 mmol/L or higher gave a prevalence of 3.8% (95% CI, 2.6%–5.0%; 36 women). With the lower cut-off level, 29% of women (12) were unaware of their diabetes, compared with 19% (7) using the higher FPG level cut-off point.

Characteristics of those identified using the lower cut-off FPG level are shown in the Table. After age-matching all patients with diabetes with control participants, diabetes was significantly associated with obesity (body mass index, > 30; odds ratio [OR], 4.2; 95% CI, 1.5–11.6) and central body fat distribution (waist/hip ratio, > 0.8; OR, 8.0; 95% CI, 2.3–25.9); and non-significantly associated with higher blood pressure (systolic, > 140 mmHg; diastolic, > 85 mmHg; OR, 2.0; 95% CI, 0.8–4.9).

The new criterion for diagnosing diabetes identifies a subgroup of the population with a high proportion of obesity and android habitus, with a tendency to higher blood pressure. The recommendation of lowering the diagnostic FPG level increases the prevalence of diabetes by an apparently small proportion, but would diagnose diabetes in an additional 34 000 women in Australia.

Characteristics (mean ± SD) of diabetic women (FPG ≥ 7.0 mmol/L) and controls (FPG < 7.0 mmol/L).

Characteristic	Diabetics (n = 41)	Controls (n = 903)	P*

Age (years)	65.1 ± 11.1	46.7 ± 17.7	< 0.0001
Weight (kg)	74.5 ± 16.2	68.6 ± 14.4	0.03
Height (cm)	158.6 ± 5.6	161.9 ± 6.5	0.0007
BMI (kg/m2)	29.6 ± 6.1	26.2 ± 5.3	0.001
Waist/hip ratio	0.88 ± 0.06	0.80 ± 0.07	< 0.0001
Systolic BP (mmHg)	139 ± 21	121 ± 21	< 0.0001
Diastolic BP (mmHg)	83 ± 16	76 ± 12	0.007

* t test. FPG = fasting plasma glucose; BMI = body mass index; BP = blood pressure.

Acknowledgement: The study was supported by grants from the Victorian Health Promotion Foundation.

American Diabetes Association. Report of the expert committee on the diagnosis and classification of diabetes mellitus. Diabetes Care 1997; 20: 1183-1197. <PubMed>
World Health Organization. Definition, diagnosis and classification of diabetes mellitus and its complications. Report of a WHO Consultation. Part 1: diagnosis and classification of diabetes mellitus. Geneva: World Health Organization Department of Noncommunicable Disease Surveillance, 1999: 1-59.
Colagiuri S, Colagiuri R, Ward J. National diabetes strategy and implementation plan. Canberra: Diabetes Australia, 1998.
Hilton DJ, O'Rourke PK, Welborn TA, Reid CM. Diabetes detection in Australian general practice: a comparison of diagnostic criteria. Med J Aust 2002; 176: 104-107. <eMJA full text> <PubMed>
Henry MJ, Pasco JA, Nicholson GC, et al. Prevalence of osteoporosis in Australian women: Geelong Osteoporosis Study. J Clin Densitom 2000; 3: 261-268. <PubMed>

(Received 25 Feb 2002, accepted 7 Mar 2002)

The University of Melbourne, Department of Clinical and Biomedical Sciences, Barwon Health, Geelong, VIC.

Julie A Pasco, PhD, Coordinator, Geelong Osteoporosis Study; Mark A Kotowicz, MB BS, FRACP, Associate Professor of Medicine; Margaret J Henry, PhD, Mathematician/Statistician; Geoffrey C Nicholson, PhD, FRACP, FRCP, Professor of Medicine.

Correspondence: Dr Julie A Pasco, The University of Melbourne, Department of Clinical and Biomedical Sciences, Barwon Health, PO Box 281, Geelong, VIC 3220. juliepATbarwonhealth.org.au

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