The "muffin test"--an alternative to the oral glucose tolerance test for detecting impaired glucose tolerance.

OBJECTIVE

The aim of this study was to compare the effectiveness of the "muffin test" (MT) with that of the oral glucose tolerance test (OGTT) in diagnosing impaired glucose tolerance (IGT).

METHODS

This is a cross-sectional study in a single academic institution. The participants were 73 women aged 42 to 58 years, less than 36 months after menopause, recruited for the Kronos Early Estrogen Prevention Study Trial. After a 10-hour fasting blood draw, the participants were provided a muffin and a beverage. Two-hour glucose levels were assessed. A subset underwent metabolic testing consisting of an OGTT (n = 12) and a mixed-meal tolerance test (n = 10). The main outcome measures were the prevalence of IGT and 2-hour glucose measurements after each testing method.

RESULTS

Two-hour glucose levels were linearly related to fasting values by multivariable linear regression. This association was exaggerated in overweight (body mass index, 25 kg/m2) women (coefficient, 1.43; P < 0.001). Two-hour OGTT and MT glucose levels were comparable (P > 0.05); 2-hour glucose levels after OGTT were slightly lower than after the mixed-meal tolerance test (P < 0.05).

CONCLUSIONS

The prevalence of IGT was 11% (8 of 73). Fasting plasma glucose alone would have missed 63% of cases (five of eight cases). The MT demonstrated 100% sensitivity and specificity for diagnosing IGT compared with the gold standard OGTT. This small pilot study should be confirmed in a larger prospective group of participants.