LA CONSULTA SEMANAL

NOVIEMBRE 2000

CONSULTA

Diabetes Care 2000 Sep;23(9):1440-1 [Texto completo]
Assessment of insulin secretion from the oral glucose tolerance test in white patients with type 2 diabetes.
Stumvoll M, Mitrakou A, Pimenta W, Jenssen T, Yki-Jarvinen H, Van Haeften T, Haring H, Fritsche A, Gerich J

Diabetes Care 2000 Mar;23(3):295-301 [Texto completo]
Use of the oral glucose tolerance test to assess insulin release and insulin sensitivity.
Stumvoll M, Mitrakou A, Pimenta W, Jenssen T, Yki-Jarvinen H, Van Haeften T, Renn W, Gerich J Abteilung IV, Medizinische Klinik der Universitat Tubingen, Germany.
OBJECTIVE: The oral glucose tolerance test (OGTT) has often been used to evaluate apparent insulin release and insulin resistance in various clinical settings. However, because insulin sensitivity and insulin release are interdependent, to what extent they can be predicted from an OGTT is unclear. RESEARCH DESIGN AND METHODS: We studied insulin sensitivity using the euglycemic-hyperinsulinemic clamp and insulin release using the hyperglycemic clamp in 104 nondiabetic volunteers who had also undergone an OGTT. Demographic parameters (BMI, waist-to-hip ratio, age) and plasma glucose and insulin values from the OGTT were subjected to multiple linear regression to predict the metabolic clearance rate (MCR) of glucose, the insulin sensitivity index (ISI), and first-phase (1st PH) and second-phase (2nd PH) insulin release as measured with the respective clamps. RESULTS: The equations predicting MCR and ISI contained BMI, insulin (120 min), and glucose (90 min) and were highly correlated with the measured MCR (r = 0.80, P < 0.00005) and ISI (r = 0.79, P < 0.00005). The equations predicting 1st PH and 2nd PH contained insulin (0 and 30 min) and glucose (30 min) and were also highly correlated with the measured 1st PH (r = 0.78, P < 0.00005) and 2nd PH (r = 0.79, P < 0.00005). The parameters predicted by our equations correlated better with the measured parameters than homeostasis model assessment for secretion and resistance, the delta30-min insulin/delta30-min glucose ratio for secretion and insulin (120 min) for insulin resistance taken from the OGTT. CONCLUSIONS: We thus conclude that predicting insulin sensitivity and insulin release with reasonable accuracy from simple demographic parameters and values obtained during an OGTT is possible. The derived equations should be used in various clinical settings in which the use of clamps or the minimal model would be impractical.

Diabetes Care 2000 May;23(5):714-5 [Texto completo]
Is there any use for the oral glucose tolerance test?
Vaccaro O, Ruffa G, Riccardi G
Publication Types:
  Comment
  Letter
Comments:
  Comment on: Diabetes Care 1999 Mar;22(3):399-402
  Comment on: Diabetes Care 1999 Sep;22(9):1490-3
  Comment on: Diabetes Care 1999 Nov;22(11):1919-20

Am J Obstet Gynecol 2000 May;182(5):1052-4
Oral glucose tolerance test and the preparatory diet.
Crowe SM, Mastrobattista JM, Monga M
Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Texas Health Science Center at Houston, 77030, USA.
OBJECTIVE: A 3-day diet containing at least 150 g carbohydrate per day has been used in many centers in preparation for the oral glucose tolerance test. The preparatory diet is thought to reduce false-positive diagnoses of gestational diabetes. The purpose of this study was to evaluate the necessity of a 3-day preparatory diet containing > or =150 g carbohydrate in otherwise healthy pregnant patients. STUDY DESIGN: Twenty healthy obstetric patients with abnormal results on a 1-hour glucose challenge test (> or =140 mg/dL) were enrolled in this prospective pilot study. Two oral glucose tolerance tests wer administered. The first was with no dietary restrictions, and the second test was performed after a 3-day diet containing at least 150 g carbohydrate. Patients were given a 3-day dietary supplement, which contained 150 g carbohydrate per day. A food diary verified compliance with the diet and indicated other food intake. RESULTS: There was no difference in the number of oral glucose tolerance tests with abnormal results, with or without the diet (5 in each group). Additionally, no significant difference was found in the mean glucose values in the diet versus no-diet groups. CONCLUSION: A preparatory diet does not significantly alter the results of an oral glucose tolerance test administered to healthy pregnant women. The diet unnecessarily delays the diagnosis of gestational diabetes.
Publication Types:
  Clinical trial
  Controlled clinical trial

CMAJ 2000 Apr 4;162(7):993-6 [Texto completo]
Dilution of the 75-g oral glucose tolerance test increases postprandial glycemia: implications for diagnostic criteria.
Sievenpiper JL, Jenkins DJ, Josse RG, Vuksan V
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ont.
BACKGROUND: Dilution has been noticed to increase the glycemic response to various sugars, including glucose. This effect may contribute to the poor reproducibility of the oral glucose tolerance test (OGTT). To test this hypothesis we assessed the effect of diluting a 75-g OGTT on 2-hour postprandial blood glucose based diagnostic outcomes, incremental glycemia and area under the glucose curve. METHODS: On 3 different occasions, 10 subjects (mean age 40 [and standard error of the mean (SEM) 3.2] years; mean body mass index 27.2 [and SEM 1.2] kg/m2) without previously diagnosed dysglycemia were given a 300-mL, 600-mL or 900-mL 75-g OGTT in random order. The protocol followed the American Diabetes Association's guidelines. Finger-prick capillary blood samples were obtained at fasting and then 15, 30, 45, 60, 90 and 120 minutes after the start of the test. RESULTS: At 30, 45 and 60 minutes, incremental glycemic concentrations were significantly higher with the 900-mL meal (means [and SEMs]: 4.9 [0.4] mmol/L, 5.1 [0.6] mmol/L and 4.6 [0.8] mmol/L, respectively) than with the 600-mL (means [and SEMs]: 4.0 [0.3] mmol/L, 4.2 [0.6] mmol/L and 3.6 [0.7] mmol/L, respectively) and the 300-mL meals (means and [SEMs]: 3.8 [0.5] mmol/L, 4.0 [0.5] mmol/L and 3.2 [0.6] mmol/L, respectively) (p < 0.05). The same was true for peak incremental blood glucose, regardless of time (p < 0.05). The area under the curve for the 900-mL meal (mean [and SEM] 404 [57] min.mmol/L) was significantly higher than for the 600-mL (mean [and SEM] 331 [51] min.mmol/L) and 300-mL meals (mean [and SEM] 280 [48] min.mmol/L) (p < 0.05). No other significant differences were observed. INTERPRETATION: Dilution of the 75-g OGTT will likely not affect current screening practices that use 2-h postprandial glucose levels as the basis for diagnosis. It may, however, bias the interpretation of older criteria that rely on intermediate time points because these midpoints appear to be sensitive to alterations in the total volume of the meal ingested.
Comments:
  Comment in: CMAJ 2000 Aug 22;163(4):387

J Hypertens 2000 Jan;18(1):83-8
Insulin levels during fasting and the glucose tolerance test and Homa's index predict subsequent development of hypertension.
Kashiwabara H, Inaba M, Maruno Y, Morita T, Awata T, Negishi K, Iitaka M, Katayama S
The Fourth Department of Medicine, Saitama Medical School, Irumagun, Japan.
OBJECTIVE: To determine whether there is a longitudinal relationship between hypertension and hyperinsulinemia and to find the most useful parameter(s) for predicting the subsequent development of hypertension. SUBJECTS AND METHODS: The oral glucose (75 g) tolerance test (OGTT) was performed in 313 patients, who were divided into three groups according to glucose tolerance based on the WHO criteria: normal, borderline and diabetes mellitus. The fasting insulin (IRI) levels, sigmaIRI (the sum of the insulin levels 0, 30, 60 and 120 min after the OGTT), insulinogenic index and Homa's index, a candidate for the simple assessment of insulin sensitivity, of the normotensive and hypertensive subjects in each subgroup were compared. In addition, 145 normotensive subjects were followed up for over 3 years and observed for the development of hypertension. RESULTS: Hypertensive diabetic subjects had not only higher fasting IRI levels and sigmaIRI values, but they also had higher Homa's indices than normotensive diabetics. Normotensive subjects with normal glucose tolerance (n = 20) did not develop hypertension. However, 16 out of 94 patients with borderline glucose tolerance and five out of 31 diabetics became hypertensive. The incidence of hypertension in the group with fasting IRI > or = 15, sigmaIRI > or = 150 or Homa's index > or = 4 was between 5 and 9 times higher than that in the group with fasting IRI < 10, sigmaIRI < 100 or Homa's index < 2. This difference was still significant when multivariate analysis, including various factors such as age, body mass index (BMI) and sex, was performed. CONCLUSIONS: These results suggest that higher plasma IRI levels and/or insulin resistance are closely related to the pathogenesis of hypertension in patients with diabetes mellitus. Homa's index, fasting and sigmaIRI may be useful predictors of the subsequent development of hypertension.

Am J Perinatol 1999;16(6):269-75
Treatment of women with an abnormal glucose challenge test (but a normal oral glucose tolerance test) decreases the prevalence of macrosomia.
Bevier WC, Fischer R, Jovanovic L
Sansum Medical Research Institute, Santa Barbara, California 93105, USA.
Infant macrosomia is a serious medical concern. Pregnant women who do not meet the specific diagnosis for gestational diabetes may still have glucose-mediated macrosomia. In Santa Barbara County all pregnant women are screened for gestational diabetes at 24-28 weeks with a 50-g, 1-hr glucose challenge test (GCT). All patients who fail this test are placed on a standard euglycemic diet (40% carbohydrate, 20% protein, 40% fat) and perform home glucose monitoring of fasting and postprandial glucose levels. The objective of this study was to examine the effectiveness of this treatment program in decreasing infant macrosomia, maternal and infant morbidity, maternal complications, and operative delivery. We studied 103 women who had a positive GCT, but a negative 100-g, 3-hr oral glucose tolerance test (OGTT). The women were randomly assigned to either experimental or control groups with experimental women receiving dietary counseling and home glucose monitoring instruction (HBGM). HBGM diaries were reviewed weekly by clinic nurses. All women had hemoglobin A1c (HbA1c) tests at 28 and 32 weeks. Maternal and fetal charts were reviewed to determine delivery type and complications, indications for cesarean section (C-section), and infant gestational age, gender, Apgar scores, birth weight, morbidities, and congenital anomalies. Of the 103 women, 5 women required insulin treatment, 1 woman had an abortion, and 14 women were indeterminate regarding compliance or were control women who received diet counseling and HBGM. The results are based on 83 women--48 control and 35 experimental. There were no significant differences between the groups for age, parity, or weight at 28-30 weeks or 37 weeks to delivery, or HbA1c at 28 weeks. HbA1c was significantly higher in control women at 32 weeks. Birth weight expressed in grams or as a percentile specific for gender, ethnicity, and gestational age was significantly higher in control infants. Birth weight was significantly correlated with maternal intake weight, weight at 28-30 weeks, and weight at delivery and with HbA1c at 32 weeks' gestation. There were no significant differences between groups for maternal complications. Groups were significantly different for mode of delivery with experimental women having more induced vaginal deliveries but fewer repeat C-sections than control women. Groups were not different for primary C-sections. Women who fail the GCT, but not the OGTT and thus do not receive the diagnosis of GDM are still at risk for delivering a macrosomic infant and operative delivery. Our program of treatment for all women who fail the GCT improves outcome by reducing infant birth weight and the number of cesarean sections.
Publication Types:
  Clinical trial
  Randomized controlled trial

Eur J Obstet Gynecol Reprod Biol 1999 Sep;86(1):29-34
Postpartum oral glucose tolerance tests in mothers of macarosomic infants: inadequacy of current antenatal test criteria in detecting prediabetic state.
Bukulmez O, Durukan T
Department of Obstetrics and Gynecology, Hacettepe University School of Medicine, Ankara, Turkey. obukulmez@hotmail.com
OBJECTIVE: To assess the presence of subtle carbohydrate metabolism abnormalities in otherwise healthy mothers who have given macrosomic birth by utilizing postpartum oral glucose tolerance test (PPOGTT). STUDY DESIGN: Prospective controlled study enrolled gestational diabetic women (GDM, n=10), mothers with macrosomic infants (MwMIs, n=62) and controls (n=50). RESULTS: Receiver operating characteristic (ROC) curve analysis revealed that incremental 1-h+2-h PPOGTT value >111 mg/dl had a sensitivity of 80% and specificity of 78% in predicting antecedent diabetes. PPOGTT results were positive in 53.2% of MwMIs and 28% of controls (P<0.01). Maternal low-density lipoprotein and triglyceride levels, 50 gram glucose challenge test (50 g GCT) values and neonatal weight were the significant predictors of PPOGTT results. ROC analyses suggested that threshold of 50 g GCT should be lowered in order to better predict subjects with both macrosomia and positive PPOGTT. CONCLUSION: PPOGTT may identify a subset of women with macrosomic infants who have metabolic alterations of a prediabetic state. The discrepancies between antenatal and postpartum tests may reflect the need for redefinition of currently utilized criteria in screening and diagnosis of GDM.

Medicina (B Aires) 1998;58(6):728-32
[Comparative study of glycosylated hemoglobin with oral glucose tolerance test in a selected population].
Vines GB, Roubicek M, Gonzalez Sanguineti A
Hospital Privado de Comunidad, Mar del Plata, Argentina. statti@infovia.com.ar
A series of 405 consecutive oral glucose tolerance tests was analyzed in comparison with simultaneous glycosylated hemoglobin (HbA1c) measurements, in order to ascertain the possible utility of HbA1c as an alternative method for diagnosis and screening in populations suspected or at increased risk of presenting diabetes mellitus. The study group consisted of 158 male and 247 nonpregnant female patients aged 3 to 84 years (median 61.5 and 56 years, respectively) referred by their physicians for diagnostic purposes. Tolerance test was performed according to usual methods and HbA1c was measured with the 2000 DC immunoassay. Results showed a good correlation between HbA1c and fasting or 2 hour glucose levels. Using WHO diagnostic criteria, HbA1c maximal normal level of 5.4% showed a sensitivity of 0.96 in distinguishing between non-diabetics and those at increased risk, for screening purposes. With HbA1c levels of 6.0 or 6.3%, specificity for a correct diagnosis of diabetes was high (0.94 or 0.97) making this a suitable level for diagnostic confirmation. With the new ADA criteria for fasting plasma glucose, the results were similar. We suggest that HbA1c measurement with highly accurate methods might be considered a valid alternative for diagnosis and screening in populations suspected or at increased risk of presenting diabetes mellitus.

Thorax 1999 Jan;54(1):40-3 [Texto completo]
Diagnosis of cystic fibrosis related diabetes: a selective approach in performing the oral glucose tolerance test based on a combination of clinical and biochemical criteria.
Yung B, Kemp M, Hooper J, Hodson ME
Department of Cystic Fibrosis, Royal Brompton Hospital, London, UK.
BACKGROUND: Cystic fibrosis related diabetes (CFRD) has become increasingly common with the increasing longevity of patients with cystic fibrosis. The diagnosis of CFRD is important as its development may lead to a clinical deterioration which may be reversed with treatment. The oral glucose tolerance test (OGTT) is the method of choice in the diagnosis of CFRD, but performing OGTTs on all patients is inconvenient for patients and labour intensive for staff. The aim of this study was to identify a more selective approach in performing OGTTs in the diagnosis of CFRD based on the use of a combination of clinical and biochemical criteria. METHODS: Clinically stable adult patients with cystic fibrosis not known to be diabetic attending the Royal Brompton Hospital Cystic Fibrosis Clinic for their annual review were invited to return within a month to have an OGTT. The result of the OGTT was compared with the results of tests performed during the annual review. The sensitivities and specificities of various methods used in the screening or diagnosis of CFRD were determined using OGTT as the "gold standard" diagnostic method. The combination of clinical and biochemical criteria which resulted in the highest sensitivity and specificity in the diagnosis of CFRD was determined. RESULTS: Between August 1996 and May 1997 122 patients became eligible for the study, 91 of whom agreed to take part. The number of patients with normal, impaired, and diabetic glucose tolerance was 58 (64%), 21 (23%), and 12 (13%), respectively. When used alone, abnormal glycosylated haemoglobin (HbA1c) was found to have the highest sensitivity (83%; 95% CI 62 to 100) in the diagnosis of CFRD. The combination of an abnormal random blood glucose and/or abnormal HbA1c and/or symptoms of hyperglycaemia or weight loss was found to have the highest sensitivity (92%; 95% CI 76 to 100) in the diagnosis of CFRD. The specificity of this combination in the diagnosis of CFRD was 79% (95% CI 70 to 88). By selectively performing OGTTs in patients with one or more of the criteria cited above, 11 of the 12 patients with OGTT defined diabetes would have been identified. CONCLUSIONS: Patients with cystic fibrosis already have to undergo a large number of routine investigations. The selective approach in performing OGTTs described here has the potential to identify the majority of patients with CFRD without the need to perform this investigation on all patients. This approach is likely to be welcomed by patients and will lead to significant savings in terms of time and resources for patients and staff. Further larger studies are warranted to validate this selective approach in the diagnosis of CFRD.
Comments:
  Comment in: Thorax 1999 Aug;54(8):751

Diabetes Res Clin Pract 1999 Jan;43(1):33-40
Prevalence of diabetes in Catalonia (Spain): an oral glucose tolerance test-based population study.
Castell C, Tresserras R, Serra J, Goday A, Lloveras G, Salleras L
Department of Health and Social Security, Autonomous Government of Catalonia, Barcelona, Spain. ccastell@dsss.scs.es
The goal of this study was to investigate the prevalence of diabetes mellitus and impaired glucose tolerance in the adult population of Catalonia and study their association with obesity, central obesity, hypertension and smoking habit. A random sample of 3839 subjects aged 30-89 years participated in this cross-sectional study: 2214 subjects underwent a health examination with oral glucose tolerance test (OGTT) and 1625 were interviewed by phone. Diabetes prevalence (known and unknown) in the 30-89-year-old population was 10.3%, (95% CI: 9.1-11.6). In this age group, the prevalence rates of known diabetes, unknown diabetes and impaired glucose tolerance were 6.4, 3.9 and 11.9% in men and 6.9, 3.4 and 11.9% in women. The age adjusted prevalence to the world population for the 30-64-year-old age group was 6.1% (7.1% in men and 5.2% in women).The factors significantly associated with diabetes were age, obesity, hypertension and family history of diabetes. The high ratio of previously known diabetic cases to newly discovered ones, specially in the oldest age group, suggests good levels of awareness and medical services. The prevalence in Catalonia is similar to that observed in other Mediterranean countries.

Clin Physiol 1999 Jan;19(1):32-44
Controlled oral glucose tolerance test: evaluation of insulin resistance with an insulin infusion algorithm that forces the OGTT glycaemic curve within the normal range. A feasibility study.
Volpicelli G, Iannello S, Belfiore F
Chair of Internal Medicine, Institute of Medicina Interna e Specialita Internistiche, University of Catania Medical School, Ospedale Garibaldi, Catania, Italy.
This is a technical study to show the feasibility of a computer-controlled oral glucose tolerance test (OGTT) using a specific algorithm, consisting of an OGTT carried out while insulin is infused as required to keep glycaemia within the normal range (National Diabetes Data Group 1979 criteria). This technique allows (a) the amount of insulin (insulin area) required to maintain a normal glycaemic curve to be assessed, a parameter indicating the degree of insulin resistance; and (b) the unique parameter consisting of the insulin secretory response (C-peptide) to a normal glycaemic curve under the inhibitory feedback exerted by the insulin levels required to maintain normal glycaemia to be obtained. Preliminary results confirmed the feasibility of this approach by showing that during the test while the glycaemic area was kept normal the insulinaemic area (endogenous + infused insulin) increased markedly in obese (n = 8) and obese diabetic (n = 5) subjects compared with normal subjects (n = 6), with values of 145.10 +/- 26.71, 204.75 +/- 20.77 and 68.25 +/- 5.93 nmol l-1 min-1 respectively (P < 0.01 in both instances). In contrast, endogenous insulin secretion (C-peptide levels) remained almost unchanged. Compared with data in normal subjects, free fatty acid (FFA) values were basally elevated in the obese and obese diabetic patients, and underwent a smaller decrease during the test. The FFA areas were greater than normal in both groups of patients, suggesting that FFAs were not fully suppressible despite the highest possible insulin levels (higher insulin levels would produce hypoglycaemia). The computer-controlled OGTT might be useful for the metabolic study of patients in the clinical setting.

Diabetes Care 1998 Nov;21(11):1807-11
The 75-g glucose tolerance test in pregnancy: a reference range determined on a low-risk population and related to selected pregnancy outcomes.
Moses RG, Moses M, Russell KG, Schier GM
Illawarra Area Health Service, Wollongong, New South Wales, Australia. robertvmoses@uow.edu.au
OBJECTIVE: To determine a reference range for the 75-g glucose tolerance test (GTT) in pregnancy using a group of women at low risk for gestational diabetes mellitus (GDM) and to determine the validity of this reference range by examining selected pregnancy outcomes for glucose-tolerant women with a 2-h result on the GTT up to 1.0 mmol/l below the diagnostic level for GDM compared with treated women with GDM. RESEARCH DESIGN AND METHODS: The reference range for the GTT was determined in 573 Caucasian women with an age <25 years and a BMI of <25 kg/m2. Selected pregnancy outcomes were compared between 272 treated women with GDM (diagnosed on the basis of a 2-h glucose level > or =8.0 mmol/l) and 308 women with a 2-h glucose level of 7.0-7.9 mmol/l. RESULTS: There was 95% confidence that at least 95% of all the fasting glucose levels are < or =5.1 mmol/l(92 mg/dl) and 95% confidence that at least 95% of all the 2-h glucose levels were < or =7.8 mmol/l (140 mg/dl). Treated women with GDM had a significantly reduced rate of large-for-gestational-age infants compared with glucose-tolerant women, without any increase in the rate of small-for-gestational-age infants or obstetric interventions. CONCLUSIONS: The reference range for the GTT in pregnancy should be determined on a low-risk population rather than on a total population. Consideration should be given to lowering the fasting glucose level to 5.0 mmol/l (90 mg/dl) and the 2-h level to 7.8 mmol/ (140 mg/dl). Glucose-tolerant women below this relatively low reference range have an increased rate of large-for-gestational-age infants and may benefit from treatment.
Comments:
  Comment in: Diabetes Care 1998 Nov;21(11):1789
  Comment in: Diabetes Care 1999 Apr;22(4):653-4

Diabetologia 1998 Sep;41(9):1029-39
Assessment of insulin sensitivity and secretion with the labelled intravenous glucose tolerance test: improved modelling analysis.
Mari A
Institute of Systems Science and Biomedical Engineering, National Research Council, Padova, Italy.
A new modelling analysis was developed to assess insulin sensitivity with a tracer-modified intravenous glucose tolerance test (IVGTT). IVGTTs were performed in 5 normal (NGT) and 7 non-insulin-dependent diabetic (NIDDM) subjects. A 300 mg/kg glucose bolus containing [6,6-(2)H2]glucose was given at time 0. After 20 min, insulin was infused for 5 min (NGT, 0.03; NIDDM, 0.05 U/kg). Concentrations of tracer, glucose, insulin and C-peptide were measured for 240 min. A circulatory model for glucose kinetics was used. Glucose clearance was assumed to depend linearly on plasma insulin concentration delayed. Model parameters were: basal glucose clearance (Cl(b)), glucose clearance at 600 pmol/l insulin concentration (Cl600), basal glucose production (Pb), basal insulin sensitivity index (BSI = Cl(b)/basal insulin concentration); incremental insulin sensitivity index (ISI = slope of the relationship between insulin concentration and glucose clearance). Insulin secretion was calculated by deconvolution of C-peptide data. Indices of basal pancreatic sensitivity (PSIb) and first (PSI1) and second-phase (PSI2) sensitivity were calculated by normalizing insulin secretion to the prevailing glucose levels. Diabetic subjects were found to be insulin resistant (BSI: 2.3 +/- 0.6 vs 0.76 +/- 0.18 ml x min(-1) x m(-2) x pmol/l(-1), p < 0.02; ISI: 0.40 +/- 0.06 vs 0.13 +/- 0.05 ml x min(-1) x m(-2) x pmol/l(-1), p < 0.02; Cl600: 333 +/- 47 vs 137 +/- 26 ml x min(-1) x m(-2), p < 0.01; NGT vs NIDDM). Pb was not elevated in NIDDM (588 +/- 169 vs 606 +/- 123 micromol x min(-1) x m(-2), NGT vs NIDDM). Hepatic insulin resistance was however present as basal glucose and insulin were higher. PSI1 was impaired in NIDDM (67 +/- 15 vs 12 +/- 7 pmol x min x m(-2) x mmol/l(-1), p < 0.02; NGT vs NIDDM). In NGT and in a subset of NIDDM subjects (n = 4), PSIb was inversely correlated with BSI (r = 0.95, p < 0.0001, log transformation). This suggests the existence of a compensatory mechanism that increases pancreatic sensitivity in the presence of insulin resistance, which is normal in some NIDDM subjects and impaired in others. In conclusion, using a simple test the present analysis provides a rich set of parameters characterizing glucose metabolism and insulin secretion, agrees with the literature, and provides some new information on the relationship between insulin sensitivity and secretion.

Diabetes Care 1998 Aug;21(8):1215-6
Isn't it time to retire the oral glucose tolerance test for diabetes screening and diagnosis?
Goldstein DE
Publication Types:
  Comment
  Editorial
Comments:
  Comment on: Diabetes Care 1998 Aug;21(8):1221-5

Diabetes Care 1998 Feb;21(2):278-82
Insulin secretion in normal glucose-tolerant relatives of type 2 diabetic subjects. Assessments using hyperglycemic glucose clamps and oral glucose tolerance tests.
van Haeften TW, Dubbeldam S, Zonderland ML, Erkelens DW
Department of Internal Medicine, Utrecht University, The Netherlands. t.w.vanhaeften@digd.azu.nl
OBJECTIVE: To assess insulin secretion in normal glucose-tolerant Caucasian first-degree relatives of type 2 diabetes subjects and in matched normal glucose-tolerant control subjects and to compare insulin secretion as assessed using a hyperglycemic glucose clamp with insulin secretion as assessed using an oral glucose tolerance test (OGTT). RESEARCH DESIGN AND METHODS: Twenty-one first-degree relatives of type 2 diabetic subjects and 21 control subjects without a family history of type 2 diabetes, who were matched for sex, age, BMI, waist-to-hip ratio, and aerobic capacity, underwent a hyperglycemic glucose clamp (10 mmol/l, 180 min). An OGTT (75 g glucose in 300 ml water) was also performed. RESULTS: First-phase insulin release (plasma insulin, 0-10 min) was not different (multiple analysis of variance [MANOVA]: F = 2.63, P = 0.11) Second-phase insulin release was lower (MANOVA: F = 4.18, P = 0.047). Separate analyses of variance showed decreased plasma insulin levels from 120 min onward (all P < 0.05), decreasing to geometric mean (95% CI) levels of 330 (270-402) and 462 (366-582) pmol/l at 180 min in relatives and control subjects, respectively. The insulin sensitivity index (ISI) as assessed using a hyperglycemic clamp was not different between the two groups. Mean +/- SE ISI during the 3rd hour was 27.5 +/- 2.2 and 30.5 +/- 3.0 micrograms.kg-1.min-1.pmol-1.l-1 in relatives and control subjects, respectively (P > 0.20). At 90 min after the OGTT, log plasma insulin levels correlated significantly with second-phase insulin release as assessed using the hyperglycemic glucose clamp. CONCLUSIONS: Normal glucose-tolerant first-degree relatives of type 2 diabetic subjects have a decreased second-phase insulin release, compared with matched control subjects. After an OGTT, 90-min values of log plasma insulin and 90-min values of the ratio of log plasma insulin to blood glucose may be good indicators of insulin secretory properties in normal glucose-tolerant family members of type 2 diabetic subjects.

Obstet Gynecol 1996 Jul;88(1):156
Diagnosing gestational diabetes mellitus: use of a glucose screen without administering the glucose tolerance test.
Chez RA
Publication Types:
  Comment
  Letter
Comments:
  Comment on: Obstet Gynecol 1996 Mar;87(3):395-400

Diabetes Care 1996 Mar;19(3):271
Oral glucose tolerance tests.
Elks ML
Publication Types:
  Letter

Obstet Gynecol 1996 Mar;87(3):395-400
Diagnosing gestational diabetes mellitus: use of a glucose screen without administering the glucose tolerance test.
Landy HJ, Gomez-Marin O, O'Sullivan MJ
Division of Perinatology, Department of Obstetrics and Gynecology, University of Miami School of Medicine, Miami, FL, USA.
OBJECTIVE: To determine if a 1-hour glucose screen value could be identified, above which gestational diabetes mellitus could be diagnosed without the 3-hour oral glucose tolerance test (GTT). METHODS: Demographic, historic, obstetric, and neonatal data from 514 singleton pregnancies with glucose screen values at least 140 mg/dL followed by a GTT were reviewed (312 patients with normal GTTs and 202 with gestational diabetes mellitus). Statistical analyses used chi2, Fisher exact, Student t, and Mann-Whitney tests. After determining the optimal glucose screen cutoff point using receiver operating characteristic curve analyses, patients were regrouped according to this value and analyzed further. RESULTS: The optimal cutoff point for the upper limit of the glucose screen was determined to be 186 mg/dL (95.9% specificity, 98.2% negative predictive value, 36.1% sensitivity, and 19.6% positive predictive value). Comparison of patients with elevated screens and normal GTTs versus those with gestational diabetes revealed significant differences only regarding a history of gestational diabetes mellitus and neonatal hypoglycemia in the studied pregnancy. Those with screens greater than 185 mg/dL behaved like diabetic patients and, when compared with subjects with screens of 140-185 mg/dL, also had a significantly greater proportion of large for gestational age infants. CONCLUSION: Patients with 1-hour glucose screens greater than 185 mg/dL have a high probability of gestational diabetes mellitus and the diagnosis can be made without the GTT. Using this approach could allow prompt initiation of therapy without the inconvenience and discomfort of the GTT.
Comments:
  Comment in: Obstet Gynecol 1996 Jul;88(1):156

Diabetes Care 1995 Jul;18(7):1072-3
Is the oral glucose tolerance test obsolete?
Drash AL
Publication Types:
  Editorial

BMJ 1994 Aug 20-27;309(6953):537, 538
Tests for diagnosing diabetes mellitus. Glucose tolerance test is most sensitive.
Simon K
Publication Types:
  Comment
  Letter
Comments:
  Comment on: BMJ 1994 May 21;308(6940):1323-8