Endocrine Abstracts

We conducted a retrospective notes analysis to determine the incidence, prevalence and predictive factors of idiopathic postprandial hypoglycaemia (IPH) in a population of 230 000 served by our Hospital.

Using the Biochemistry Database all patients who had a 5-hour oral glucose tolerance test (OGTT) from 1995 to 2001 were identified, and their notes were reviewed. Demographic, clinical and biochemical data were recorded for each patient. The latter included 0 min plasma glucose (G0), nadir glucose (Gn), 300 min glucose (G300), the time that Gn occurred (GnT) and if applicable the plasma insulin. IPH was diagnosed by the presence of symptoms and a Gn less than or equal to 2.8 mmol/L, as defined by the Third International Symposium on Hypoglycaemia.

72 patients had a 5-hour OGTT, and IPH was diagnosed in 42 (58%) patients. The annual incidence and prevalence of IPH in our population is 3 and 18 per 100 000 people, respectively. There were no significant differences in <mean plus/minus SD [range]> G0 (4.8 plus/minus 0.9 [3.2-6.5] vs 4.8 plus/minus 0.7 [3.8-6.0] mmol/L) or G300 (5.4 plus/minus 1.0 [3.5-7.6] vs 5.8 plus/minus 0.7 [4.9-7.6] mmol/L) between IPH patients and those without IPH. Patients with IPH had a significantly lower Gn (2.1 plus/minus 0.5 [0.5-2.8] vs 4.9 plus/minus 0.8 [2.9-6.1] mmol/L) and a later GnT (219 plus/minus 24 [180-270] vs 176 plus/minus 36 [120-240] mins) compared to patients without IPH. The plasma insulin in IPH patients was 15.9 plus/minus 2.2 [11.9-23.4] (normal: 1.6-10.9 mU/L). Using multiple logistic regression significant predictors of IPH were a previously low recorded glucose (<odds ratio [95% CI]> 5.6 [1.4-23.0], p=0.018), female gender (4.0 [2.3-19.0], p=0.02) and symptoms relieved by food (4.4 [1.3-15.6], p=0.02).

Our data suggest that IPH is a condition that is often encountered in Endocrine practice, and that female patients who have had a previously low recorded glucose and whose symptoms are relieved by eating are highly likely to have a positive 5-hour OGTT.