Screening for Diabetes

In our Pediatric Weight Clinic in Calgary we check in all patients a HbA1C level. Essentially we are trying to see what the risk is for that patient to get Diabetes.

A recent study in Diabetes Care looked at the usefulness of the HbA1C. If it is over 6.5% it is highly specific. However some doctors prefer to use a glucose tolerance test.

Here is a copy of the study(Sourced out of Health Day News)

HbA1c ≥6.5 Percent Is Specific, Not Sensitive for T1DM
Across four studies, HbA1c ≥6.5 percent specific, but not sensitive, early indicator of T1DM in youth

                                                                         FRIDAY, Aug. 31 (HealthDay News) — Using a   glycated hemoglobin (HbA1c) threshold of ≥6.5 percent is a specific but not   sensitive early indicator of type 1 diabetes (T1D) in high-risk children and   young adults, according to a study published in the September issue of Diabetes   Care.

Kendra Vehik, Ph.D., of   the University of South Florida in Tampa, and colleagues examined the utility   of HbA1c as an alternative criterion for impaired glucose tolerance (IGT) or   T1D in high-risk individuals younger than 21 years. Participants were   recruited from four prospective studies and included 884 participants from   Type 1 Diabetes TrialNet Natural History; 587 from Diabetes Prevention   Trial-Type 1; 420 from Trial to Reduce IDDM in the Genetically at Risk; and   91 from The Environmental Determinants of Diabetes in the Young. All   participants had an HbA1c within 90 days of an oral glucose tolerance test   (OGTT) and a two-hour plasma glucose measure.

The researchers found   that using HbA1c of ≥5.7 percent as an indicator of IGT resulted in a very   low sensitivity across the studies (8 to 42 percent) and variable specificity   (64 to 95 percent). Sensitivity was very low (24 to 34 percent) and   specificity high (98 to 99 percent) using HbA1c of ≥6.5 percent as a   threshold for T1D. Across the four studies, the positive predictive value of   HbA1c varied from 50 to 94 percent.

“HbA1c ≥6.5   percent is a specific but not sensitive early indicator for T1D in high-risk   subjects <21 years of age diagnosed by OGTT or asymptomatic   hyperglycemia,” the authors write. “Redefining the HbA1c threshold   is recommended if used as an alternative criterion in diagnosing T1D.”


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