My reactions so far; others might come to mind. The numbers in your signature represent amazing, amazing reversal in 3 months prior to today's test.
Today's OGTT yielded: time 0 hour - 1 h - 2h; FPG 5.1 - 9.7 - 7.4.
1. Officially normoglycaemic, but the levels are still too high. The criterion for positivity for this test is 7.8 or higher at 2.0 h. (This makes 7.4 a near thing.) However, the only parameter taken into consideration is the 2 hour value. The test result could be negative even with a 1 h value of 14.0.
2. There was a study of OGTT results in normoglycaemic subjects. There was a wide variety of glucose disposal agility among them. But for peak postprandial value (peak, not 2 h), no subgroup had an average greater than 7.8. This tells me that >7.8 is pathological. 9.7 is absolutely pathological, because it's very close to the renal threshold (the could be slight individual variation in the renal threshold, too). My peak used to be >10.0 and probably still is.
3. Another study using the OGTT concluded that the criterion of 8.6 at 1.0 h was statistically a better predictor of progression to diabetes than 7.8 at 2.0 h. This is just one study. The rest of the diabetes world did not pursue this finding.
4. When somebody used the phrase, "better predictor", I assume they were referring to predictor of progression to diabetes (within 5 to 10 years). We might put 'progression diabetes prediction' into the search engine, to compare the three diagnostic tests.
5. When taking the OGTT, it's not desirable to be anywhere near 7.8 at 2 h still. If it is taking 3 or 4 hours to regain fasting level after eating only sugar, then you need the saving grace of lower peak levels, perhaps 7.0. Granted, hyperglycaemia consists in the postprandial response being too high and/or too wide (time dimension). Nevertheless, if you are thinking big, i.e. aiming to fully reverse hyperglycaemic test results, that entails aiming to shrink below 7.0 mmol/l and below 2.0 h. The A1c is the average of 12 weeks worth of fasting BG's and postprandial glucose response curves. Each area under a postprandial hump (response curve) -- i.e., every meal -- will increment the A1c. Lowering the A1c entails some combination of lowering the baseline and shrinking the humps.
6. The biggest clinical shortcoming of the OGTT is that it's very inconsistent. Repetitions are fairly likely to be some positive, some negative. This is discussed in two articles, pro and con, from October 2002. (Diabetes Care magazine, 25(10), care.diabetesjournals.org > issue archive.) Point: a glucose tolerance test is important for clinical practice. DOI: 10.2337. Counterpoint: the oral glucose tolerance test is superfluous. DOI: 10.2337.
7. It's nice that both insulin and glucose were measured every half hour. With this data, you could try to do some arithmetic and compare the result to Figure 3 in this article (DeFronzo 2009 April,
http://diabetes.diabetesjournals.org/content/58/4/773). I suppose for the IR, he used HOMA-IR (it'll be disclosed in the article). The measurements at 0 hours will yield this value, then you can plot it on the HOMA-IR graph (online).
8. It's a pity that they still use these backward tests, the fasting and the OGTT. They should already be taping a continuous meter to one's belly for 3 days, or a week.
