1. A study on seven Caucasian glucose-tolerant women with previous gestational diabetes and seven matched control subjects is presented. The insulin response to oral glucose, insulin sensitivity and fasting glucose production rates were measured by using a 75 g oral glucose tolerance test, an insulin tolerance test and a non-radioactive tracer, [6,6-2H]glucose, respectively.
2. Fasting plasma glucose levels were similar between the women with previous gestational diabetes and the control subjects (4.8 ± 0.3 versus 4.7 ± 0.2 mmol/l), as were fasting plasma insulin levels (median 4 m-units/l, range 1–13 m-units/l versus median 4 m-units/l, range 1–24 m-units/l). After oral glucose the 60 min plasma glucose levels in the women with previous gestational diabetes were significantly higher (8.5 ± 0.6 versus 6.7 ± 0.8 mmol/l, P < 0.05), whereas the plasma insulin level was significantly lower at both 30 min (median 23 m-units/l, range 4–47 m-units/l versus median 55 m-units/l, range 23–100 m-units/l, P < 0.02) and at 60 min (median 23 m-units/l, range 4–43 m-units/l versus median 60 m-units/l, range 16–126 m-units/l, P< 0.02).
3. Insulin sensitivity, expressed as the slope of the regression line of plasma glucose level against time after intravenous infusion of insulin (0.05 unit/kg), was similar in the women with previous gestational diabetes and the control subjects (mean slope, −0.17 ± 0.01 versus −0.17 ± 0.01).
4. Fasting glucose production rates were similar in the women with previous gestational diabetes and the control subjects (2.2 ± 0.3 versus 1.9 ± 0.1 mg min−1 kg−1).
5. Women with previous gestational diabetes, a group at risk of future non-insulin-dependent diabetes, have abnormalities of insulin release at a time when insulin sensitivity and fasting glucose production are normal.
Comparison of the homeostasis model assessment and quantitative insulin sensitivity check index with data from forearm metabolic studies for the in vivo assessment of insulin sensitivity