We have recently proposed a series of indexes for β-cell function and insulin sensitivity to be calculated from glucose and insulin concentrations obtained during a classic World Health Organization oral glucose tolerance test (OGTT) (1). The models were validated by the euglycemic-hyperinsulinemic and the hyperglycemic clamp technique, respectively. The generation of these indexes was based on simple statistical models using stepwise linear regression analysis. The variables in the model assumed the availability of determinations at 0, 30, 60, 90, and 120 min. Since the publication of this article, we have been contacted repeatedly by potential users of the indexes who do not have at their disposal all of the time points required for the various indexes.

Therefore, we returned to the original database of OGTTs and euglycemic and hyperglycemic clamps in the 104 nondiabetic subjects (normal glucose tolerance, n = 65; impaired glucose tolerance, n = 39) and generated the equations for different sets of time points. The exact same procedures were applied as previously described (1), except the indicated variables only were entered in the model. The equations were generated using both pure OGTT data and OGTT data plus demographic data (BMI, age, and waist-to-hip ratio). The resulting equations with the variables remaining in the equations are shown in Tables 1 and 2. The r values for the insulin secretion parameters ranged from 0.65 to 0.79 and for insulin sensitivity from 0.59 to 0.79. For comparison, the homeostasis model assessment (HOMA) resistance index was reasonably well correlated with the insulin sensitivity index (r = −0.59, P < 0.001) and the metabolic clearance rate (r = −0.56, P < 0.001), and the HOMA secretion index was reasonably well correlated with first-phase (r = 0.57, P < 0.001) and second-phase insulin release (r = 0.62, P < 0.001), as previously reported (1).

In conclusion, given many variations in oral glucose tolerance, reasonable estimates for insulin secretion and insulin sensitivity can be made. The optimal sampling constellation appears to be 0, 30, and 120 min, including age and BMI (all r values >0.78).

Table 1 —

Estimates of insulin sensitivity based on availability of sampling time points in nondiabetic subjects

Sampling timesEstimated insulin sensitivity index (μmol · kg–1 · min–1 · pmol/l)Estimated metabolic clearance rate (ml · kg–1 · min–1)
0 and 120 min 0.156 − 0.0000459 × Ins120 − 0.000321 × Ins0 − 0.00541 × Gluc120 13.273 − 0.00384 × Ins120 − 0.0232 × Ins0 − 0.463 × Gluc120 
 r = 0.69 r = 0.68 
0, 60, and 120 min 0.156 − 0.0000459 × Ins120 − 0.000321 × Ins0 − 0.00541 × Gluc120 13.273 − 0.00384 × Ins120 − 0.0232 × Ins0 − 0.463 × Gluc120 
 r = 0.69 r = 0.68 
0 and 30 min 0.205 − 0.000437 × Ins0 − 0.0185 × Gluc0 15.841 − 0.0341 × Ins0 − 1.262 × Gluc0 
 r = 0.62 r = 0.59 
0, 30, and 60 min 0.149 − 0.000467 × Ins0 − 0.00466 × Gluc60 12.464 − 0.0357 × Ins0 − 0.376 × Gluc60 
 r = 0.65 r = 0.62 
0 and 120 min* 0.222 − 0.00333 × BMI − 0.0000779 × Ins120 − 0.000422 × Age 19.240 − 0.281 × BMI − 0.00498 × Ins120 − 0.333 × Gluc120 
 r = 0.79 r = 0.79 
0, 60, and 120 min* 0.222 − 0.00333 × BMI − 0.0000779 × Ins120 − 0.000422 × Age 19.240 − 0.281 × BMI − 0.00498 × Ins120 − 0.333 × Gluc120 
 r = 0.79 r = 0.79 
0 and 30 min* 0.213 − 0.00305 × BMI − 0.000308 × Ins0 − 0.000640 × Age 18.078 − 0.267 × BMI − 0.0214 × Ins0 − 0.0501 × Age 
 r = 0.75 r = 0.75 
0, 30, and 60 min* 0.231 − 0.00296 × BMI − 0.000284 × Ins0 − 0.000506 × Age − 0.00318 × Gluc60 19.487 − 0.260 × BMI − 0.254 × Gluc60 − 0.0195 × Ins0 − 0.0394 × Age 
 r = 0.78 r = 0.77 
Sampling timesEstimated insulin sensitivity index (μmol · kg–1 · min–1 · pmol/l)Estimated metabolic clearance rate (ml · kg–1 · min–1)
0 and 120 min 0.156 − 0.0000459 × Ins120 − 0.000321 × Ins0 − 0.00541 × Gluc120 13.273 − 0.00384 × Ins120 − 0.0232 × Ins0 − 0.463 × Gluc120 
 r = 0.69 r = 0.68 
0, 60, and 120 min 0.156 − 0.0000459 × Ins120 − 0.000321 × Ins0 − 0.00541 × Gluc120 13.273 − 0.00384 × Ins120 − 0.0232 × Ins0 − 0.463 × Gluc120 
 r = 0.69 r = 0.68 
0 and 30 min 0.205 − 0.000437 × Ins0 − 0.0185 × Gluc0 15.841 − 0.0341 × Ins0 − 1.262 × Gluc0 
 r = 0.62 r = 0.59 
0, 30, and 60 min 0.149 − 0.000467 × Ins0 − 0.00466 × Gluc60 12.464 − 0.0357 × Ins0 − 0.376 × Gluc60 
 r = 0.65 r = 0.62 
0 and 120 min* 0.222 − 0.00333 × BMI − 0.0000779 × Ins120 − 0.000422 × Age 19.240 − 0.281 × BMI − 0.00498 × Ins120 − 0.333 × Gluc120 
 r = 0.79 r = 0.79 
0, 60, and 120 min* 0.222 − 0.00333 × BMI − 0.0000779 × Ins120 − 0.000422 × Age 19.240 − 0.281 × BMI − 0.00498 × Ins120 − 0.333 × Gluc120 
 r = 0.79 r = 0.79 
0 and 30 min* 0.213 − 0.00305 × BMI − 0.000308 × Ins0 − 0.000640 × Age 18.078 − 0.267 × BMI − 0.0214 × Ins0 − 0.0501 × Age 
 r = 0.75 r = 0.75 
0, 30, and 60 min* 0.231 − 0.00296 × BMI − 0.000284 × Ins0 − 0.000506 × Age − 0.00318 × Gluc60 19.487 − 0.260 × BMI − 0.254 × Gluc60 − 0.0195 × Ins0 − 0.0394 × Age 
 r = 0.78 r = 0.77 

Insulin (Ins) measured in picomoles per liter; glucose (Gluc) measured in millimoles per liter.

*

Inclusion of demographic parameters (age, sex, BMI, and waist-to-hip ratio) in model. All P values < 0.001.

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Table 2 —

Estimates of β-cell function based on availability of sampling time points in nondiabetic subjects

Sampling timesEstimated first phase (pmol/l)Estimated second phase (pmol/l)
0 and 120 min 2,503 + 6.476 × Ins0 − 126.5 × Gluc120 + 0.954 × Ins120 − 239.3 × Gluco 393 + 1.163 × Ins0 − 40.72 × Gluc120 + 0.313 × Ins120 
 r = 0.65 r = 0.70 
0, 60, and 120 min 1,194 + 4.724 × Ins0 − 117.0 × Gluc60 + 1.414 × Ins60 295 + 0.349 × Ins60 − 25.72 × Gluc60 + 1.107 × Ins0 
 r = 0.71 r = 0.75 
0 and 30 min 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 
0, 30, and 60 min 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 
0 and 120 min* 2,032 + 4.681 × Ins0 − 135.0 × Gluc120 + 0.995 × Ins120 + 27.99 × BMI − 269.1 × Gluc0 277 + 0.800 × Ins0 − 42.79 × Gluc120 + 0.321 × Ins120 + 5.338 × BMI r = 0.73 
 r = 0.68 
0, 60, and 120 min* 728 + 3.537 × Ins0 − 120.3 × Gluc60 + 1.341 × Ins60 + 21.27 × BMI 208 + 0.335 × Ins60 − 26.33 × Gluc60 + 0.887 × Ins0 + 3.933 × BMI 
 r = 0.73 r = 0.76 
0 and 30 min* 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 
0, 30, and 60 min* 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 
Sampling timesEstimated first phase (pmol/l)Estimated second phase (pmol/l)
0 and 120 min 2,503 + 6.476 × Ins0 − 126.5 × Gluc120 + 0.954 × Ins120 − 239.3 × Gluco 393 + 1.163 × Ins0 − 40.72 × Gluc120 + 0.313 × Ins120 
 r = 0.65 r = 0.70 
0, 60, and 120 min 1,194 + 4.724 × Ins0 − 117.0 × Gluc60 + 1.414 × Ins60 295 + 0.349 × Ins60 − 25.72 × Gluc60 + 1.107 × Ins0 
 r = 0.71 r = 0.75 
0 and 30 min 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 
0, 30, and 60 min 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 
0 and 120 min* 2,032 + 4.681 × Ins0 − 135.0 × Gluc120 + 0.995 × Ins120 + 27.99 × BMI − 269.1 × Gluc0 277 + 0.800 × Ins0 − 42.79 × Gluc120 + 0.321 × Ins120 + 5.338 × BMI r = 0.73 
 r = 0.68 
0, 60, and 120 min* 728 + 3.537 × Ins0 − 120.3 × Gluc60 + 1.341 × Ins60 + 21.27 × BMI 208 + 0.335 × Ins60 − 26.33 × Gluc60 + 0.887 × Ins0 + 3.933 × BMI 
 r = 0.73 r = 0.76 
0 and 30 min* 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 
0, 30, and 60 min* 1,283 + 1.829 × Ins30 − 138.7 × Gluc30 + 3.772 × Ins0 286 + 0.416 × Ins30 − 25.94 × Gluc30 + 0.926 × Ins0 
 r = 0.78 r = 0.79 

Insulin (Ins) measured in picomoles per liter; glucose (Gluc) measured in millimoles per liter.

*

Inclusion of demographic parameters (age, sex, BMI, and waist-to-hip ratio) in model. All P values < 0.001.

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1.
Stumvoll M, Mitrakou A, Pimenta W, Jenssen T, Yki-Järvinen H, Van Haeften TW, Renn W, Gerich J: Use of the oral glucose tolerance test to assess insulin release and insulin sensitivity.
Diabetes Care
 
23
:
295
–301,
2000

Address correspondence to Dr. Michael Stumvoll, Medizinische Universitätsklinik, Otfried-Müller-Str. 10, D-72076 Tübingen, Germany.

2001