Maternal plasma cortisol's effect on offspring birth weight: a Mendelian Randomisation study.

BACKGROUND: Observational studies and randomized controlled trials have found evidence that higher maternal circulating cortisol levels in pregnancy are associated with lower offspring birth weight. However, it is possible that the observational associations are due to residual confounding. METHODS: We performed two-sample Mendelian Randomisation (MR) using a single genetic variant (rs9989237) associated with morning plasma cortisol (GWAS; sample 1; N = 25,314). The association between this maternal genetic variant and offspring birth weight, adjusted for fetal genotype, was obtained from the published EGG Consortium and UK Biobank meta-analysis (GWAS; sample 2; N = up to 406,063) and a Wald ratio was used to estimate the causal effect. We also performed an alternative analysis using all GWAS reported cortisol variants that takes account of linkage disequilibrium. We also tested the genetic variant's effect on pregnancy cortisol and performed PheWas to search for potential pleiotropic effects. RESULTS: The estimated effect of maternal circulating cortisol on birth weight was a 50 gram (95% CI, -109 to 10) lower birth weight per 1 SD higher log-transformed maternal circulating cortisol levels, using a single variant. The alternative analysis gave similar results (-33 grams (95% CI, -77 to 11)). The effect of the cortisol variant on pregnancy cortisol was 2-fold weaker than in the original GWAS, and evidence was found of pleiotropy. CONCLUSIONS: Our findings provide some evidence that higher maternal morning plasma cortisol causes lower birth weight. Identification of more independent genetic instruments for morning plasma cortisol are necessary to explore the potential bias identified.

Clinical profiles of post-load glucose subgroups and their association with glycaemic traits over time: An IMI-DIRECT study.

AIM: To examine the hypothesis that, based on their glucose curves during a seven-point oral glucose tolerance test, people at elevated type 2 diabetes risk can be divided into subgroups with different clinical profiles at baseline and different degrees of subsequent glycaemic deterioration. METHODS: We included 2126 participants at elevated type 2 diabetes risk from the Diabetes Research on Patient Stratification (IMI-DIRECT) study. Latent class trajectory analysis was used to identify subgroups from a seven-point oral glucose tolerance test at baseline and follow-up. Linear models quantified the associations between the subgroups with glycaemic traits at baseline and 18 months. RESULTS: At baseline, we identified four glucose curve subgroups, labelled in order of increasing peak levels as 1-4. Participants in Subgroups 2-4, were more likely to have higher insulin resistance (homeostatic model assessment) and a lower Matsuda index, than those in Subgroup 1. Overall, participants in Subgroups 3 and 4, had higher glycaemic trait values, with the exception of the Matsuda and insulinogenic indices. At 18 months, change in homeostatic model assessment of insulin resistance was higher in Subgroup 4 (ß = 0.36, 95% CI 0.13-0.58), Subgroup 3 (ß = 0.30; 95% CI 0.10-0.50) and Subgroup 2 (ß = 0.18; 95% CI 0.04-0.32), compared to Subgroup 1. The same was observed for C-peptide and insulin. Five subgroups were identified at follow-up, and the majority of participants remained in the same subgroup or progressed to higher peak subgroups after 18 months. CONCLUSIONS: Using data from a frequently sampled oral glucose tolerance test, glucose curve patterns associated with different clinical characteristics and different rates of subsequent glycaemic deterioration can be identified.

Type 1 diabetes genetic risk score discriminates between monogenic and Type 1 diabetes in children diagnosed at the age of <5 years in the Iranian population.

AIM: To examine the extent to which discriminatory testing using antibodies and Type 1 diabetes genetic risk score, validated in European populations, is applicable in a non-European population. METHODS: We recruited 127 unrelated children with diabetes diagnosed between 9 months and 5 years from two centres in Iran. All children underwent targeted next-generation sequencing of 35 monogenic diabetes genes. We measured three islet autoantibodies (islet antigen 2, glutamic acid decarboxylase and zinc transporter 8) and generated a Type 1 diabetes genetic risk score in all children. RESULTS: We identified six children with monogenic diabetes, including four novel mutations: homozygous mutations in WFS1 (n=3), SLC19A2 and SLC29A3, and a heterozygous mutation in GCK. All clinical features were similar in children with monogenic diabetes (n=6) and in the rest of the cohort (n=121). The Type 1 diabetes genetic risk score discriminated children with monogenic from Type 1 diabetes [area under the receiver-operating characteristic curve 0.90 (95% CI 0.83-0.97)]. All children with monogenic diabetes were autoantibody-negative. In children with no mutation, 59 were positive to glutamic acid decarboxylase, 39 to islet antigen 2 and 31 to zinc transporter 8. Measuring zinc transporter 8 increased the number of autoantibody-positive individuals by eight. CONCLUSIONS: The present study provides the first evidence that Type 1 diabetes genetic risk score can be used to distinguish monogenic from Type 1 diabetes in an Iranian population with a large number of consanguineous unions. This test can be used to identify children with a higher probability of having monogenic diabetes who could then undergo genetic testing. Identification of these individuals would reduce the cost of treatment and improve the management of their clinical course.

Persistent C-peptide is associated with reduced hypoglycaemia but not HbA1c in adults with longstanding Type 1 diabetes: evidence for lack of intensive treatment in UK clinical practice?

AIMS: Most people with Type 1 diabetes have low levels of persistent endogenous insulin production. The Diabetes Control and Complications Trial showed that close to diagnosis preserved endogenous insulin was associated with lower HbA1c , hypoglycaemia and complication rates, when intensively treated. We aimed to assess the clinical impact of persistent C-peptide on rate of hypoglycaemia and HbA1c in those with long duration (> 5 years) Type 1 diabetes. METHODS: We conducted a cross-sectional case-control study of 221 people (median age 24 years) with Type 1 diabetes. We confirmed ongoing endogenous insulin secretion by measuring C-peptide after a mixed-meal tolerance test. We compared self-reported hypoglycaemia (n = 160), HbA1c , insulin dose and microvascular complications (n = 140) in those with preserved and low C-peptide. RESULTS: Stimulated median (IQR) C-peptide was 114 (43, 273) pmol/l and < 3 (< 3, < 3) pmol/l in those with preserved and low C-peptide respectively. Participants with preserved C-peptide had lower reported monthly rates of hypoglycaemia, with 21% fewer symptomatic episodes, 5.9 vs. 7.5 [incidence rate ratio (IRR) 0.79, P = 0.001], and 65% fewer asymptomatic episodes, 1.0 vs. 2.9 (IRR 0.35, P < 0.001). Those with preserved C-peptide had a lower insulin dose (0.68 vs. 0.81 units/kg, P = 0.01) but similar HbA1c (preserved 69 vs. low 67 mmol/mol, P = 0.06). CONCLUSIONS: Adults with Type 1 diabetes and preserved endogenous insulin production receiving usual care in the UK have lower daily insulin doses and fewer self-reported hypoglycaemic episodes, but no difference in HbA1c . This is consistent with non-intensive treatment in previous studies, and suggests a need to consider therapy intensification to gain full benefit of preserved endogenous insulin.

Random non-fasting C-peptide: bringing robust assessment of endogenous insulin secretion to the clinic.

BACKGROUND: Measuring endogenous insulin secretion using C-peptide can assist diabetes management, but standard stimulation tests are impractical for clinical use. Random non-fasting C-peptide assessment would allow testing when a patient is seen in clinic. METHODS: We compared C-peptide at 90 min in the mixed meal tolerance test (sCP) with random non-fasting blood C-peptide (rCP) and random non-fasting urine C-peptide creatinine ratio (rUCPCR) in 41 participants with insulin-treated diabetes [median age 72 (interquartile range 68-78); diabetes duration 21 (14-31) years]. We assessed sensitivity and specificity for previously reported optimal mixed meal test thresholds for severe insulin deficiency (sCP < 200 pmol//l) and Type 1 diabetes/inability to withdraw insulin (< 600 pmol//l), and assessed the impact of concurrent glucose. RESULTS: rCP and sCP levels were similar (median 546 and 487 pmol//l, P = 0.92). rCP was highly correlated with sCP, r = 0.91, P < 0.0001, improving to r = 0.96 when excluding samples with concurrent glucose < 8 mmol//l. An rCP cut-off of 200 pmol//l gave 100% sensitivity and 93% specificity for detecting severe insulin deficiency, with area under the receiver operating characteristic curve of 0.99. rCP < 600 pmol//l gave 87% sensitivity and 83% specificity to detect sCP < 600 pmol//l. Specificity improved to 100% when excluding samples with concurrent glucose < 8 mmol//l. rUCPCR (0.52 nmol/mmol) was also well-correlated with sCP, r = 0.82, P < 0.0001. A rUCPCR cut-off of < 0.2 nmol/ mmol gave sensitivity and specificity of 83% and 93% to detect severe insulin deficiency, with area under the receiver operating characteristic curve of 0.98. CONCLUSIONS: Random non-fasting C-peptide measures are strongly correlated with mixed meal C-peptide, and have high sensitivity and specificity for identifying clinically relevant thresholds. These tests allow assessment of C-peptide at the point patients are seen for clinical care.

The association between postprandial urinary C-peptide creatinine ratio and the treatment response to liraglutide: a multi-centre observational study.

AIMS: The response to glucagon-like peptide 1 receptor agonist treatment may be influenced by endogenous ß-cell function. We investigated whether urinary C-peptide creatinine ratio assessed before or during liraglutide treatment was associated with treatment response. METHODS: A single, outpatient urine sample for urinary C-peptide creatinine ratio was collected 2 h after the largest meal of the day among two separate groups: (1) subjects initiating liraglutide (0.6 â†’ 1.2 mg daily) or (2) subjects already treated with liraglutide for 20-32 weeks. The associations between pretreatment and on-treatment urinary C-peptide creatinine ratio and HbA1c change at 32 weeks were assessed using univariate and multivariate analyses (the ratio was logarithm transformed for multivariate analyses). Changes in HbA1c according to pretreatment urinary C-peptide creatinine ratio quartiles are shown. RESULTS: One hundred and sixteen subjects (70 pretreatment, 46 on treatment) with Type 2 diabetes from 10 diabetes centres were studied. In univariate analyses, neither pretreatment nor on-treatment urinary C-peptide creatinine ratio correlated with HbA1c change (Spearman rank correlation coefficient, r = -0.17, P = 0.17 and r = -0.20, P = 0.19, respectively). In multi-linear regression analyses, entering baseline HbA1c and log urinary C-peptide creatinine ratio, pretreatment and on-treatment log urinary C-peptide creatinine ratio became significantly associated with HbA1c change (P = 0.048 and P = 0.040, respectively). Mean (sd) HbA1c changes from baseline in quartiles 1 to 4 of pretreatment urinary C-peptide creatinine ratio were -3 ± 17 mmol/mol (-0.3 ± 1.6%) (P = 0.52), -12 ± 15 mmol/mol (-1.1 ± 1.4%) (P = 0.003), -11 ± 13 mmol/mol (-1.0 ± 1.2%) (P = 0.002) and -12±17 mmol/mol (-1.1±1.6%) (P=0.016), respectively. CONCLUSIONS: Postprandial urinary C-peptide creatinine ratios before and during liraglutide treatment were weakly associated with the glycaemic response to treatment. Low pretreatment urinary C-peptide creatinine ratio may be more useful than higher values by predicting poorer glycaemic response.

The development and validation of a clinical prediction model to determine the probability of MODY in patients with young-onset diabetes.

AIMS/HYPOTHESIS: Diagnosing MODY is difficult. To date, selection for molecular genetic testing for MODY has used discrete cut-offs of limited clinical characteristics with varying sensitivity and specificity. We aimed to use multiple, weighted, clinical criteria to determine an individual's probability of having MODY, as a crucial tool for rational genetic testing. METHODS: We developed prediction models using logistic regression on data from 1,191 patients with MODY (n = 594), type 1 diabetes (n = 278) and type 2 diabetes (n = 319). Model performance was assessed by receiver operating characteristic (ROC) curves, cross-validation and validation in a further 350 patients. RESULTS: The models defined an overall probability of MODY using a weighted combination of the most discriminative characteristics. For MODY, compared with type 1 diabetes, these were: lower HbA(1c), parent with diabetes, female sex and older age at diagnosis. MODY was discriminated from type 2 diabetes by: lower BMI, younger age at diagnosis, female sex, lower HbA(1c), parent with diabetes, and not being treated with oral hypoglycaemic agents or insulin. Both models showed excellent discrimination (c-statistic = 0.95 and 0.98, respectively), low rates of cross-validated misclassification (9.2% and 5.3%), and good performance on the external test dataset (c-statistic = 0.95 and 0.94). Using the optimal cut-offs, the probability models improved the sensitivity (91% vs 72%) and specificity (94% vs 91%) for identifying MODY compared with standard criteria of diagnosis <25 years and an affected parent. The models are now available online at www.diabetesgenes.org . CONCLUSIONS/INTERPRETATION: We have developed clinical prediction models that calculate an individual's probability of having MODY. This allows an improved and more rational approach to determine who should have molecular genetic testing.

Validation of a single-sample urinary C-peptide creatinine ratio as a reproducible alternative to serum C-peptide in patients with Type 2 diabetes.

AIMS: Serum C-peptide can be used in Type 2 diabetes as a measure of endogenous insulin secretion, but practicalities of collection limit its routine clinical use. Urine C-peptide creatinine ratio is a non-invasive alternative that is stable for at least 3 days at room temperature in boric acid preservative. We aimed to assess the utility of urine C-peptide creatinine ratio in individuals with Type 2 diabetes as an alternative to serum C-peptide. METHODS: We assessed, in 77 individuals with Type 2 diabetes, the reproducibility of, and correlations between, fasting and postprandial urine C-peptide creatinine ratio and serum C-peptide, and the impact of renal impairment (estimated glomerular filtration rate < 60 ml min(-1) 1.73 m(-2)) on these correlations. RESULTS: Urine C-peptide creatinine ratio was at least as reproducible as serum C-peptide [fasting coefficient of variation mean (95% CI): 28 (21-35)% vs. 38 (26-59)% and 2-h post-meal 26 (18-33)% vs. 27 (20-34)%. Urine C-peptide creatinine ratio 2 h post-meal was correlated with stimulated serum C-peptide, both the 2-h value (r = 0.64, P < 0.001) and the 2-h area under the C-peptide curve (r = 0.63, P < 0.001). The association seen was similar in patients with and without moderate renal impairment (P = 0.6). CONCLUSIONS: In patients with Type 2 diabetes, a single urine C-peptide creatinine ratio is a stable, reproducible measure that is well correlated with serum C-peptide following meal stimulation, even if there is moderate renal impairment. Urine C-peptide creatinine ratio therefore has potential for use in clinical practice in the assessment of Type 2 diabetes.

The impact of insulin administration during the mixed meal tolerance test.

AIMS: The mixed meal tolerance test is the gold standard measure of endogenous insulin secretion. Practical issues limit the routine clinical use of this test, including omitting insulin prior to the ingestion of a high-carbohydrate liquid mixed meal, which can result in marked hyperglycaemia. We aimed to assess whether insulin omission is necessary during the mixed meal tolerance test and whether fasting C-peptide was a practical alternative to the test. METHODS: Ninety-one adults with insulin-treated diabetes (Type 1 n = 56, Type 2 n = 35) underwent two mixed meal tolerance tests; one standard without insulin and one with the patient's usual morning insulin. RESULTS: The 90-min serum C-peptide was highly correlated in the standard mixed meal tolerance test and the test with insulin (r = 0.98, P < 0.0001). There was a 20% reduction in the peak C-peptide value when insulin was given {test with insulin [0.39 (0.01-1.16) vs. test without insulin 0.48 (0.01-1.36) nmol/l, P = 0.001]}, but the original serum C-peptide cut-off for significant endogenous insulin secretion (≥ 0.2 nmol/l) still correctly classified 90/91 patients (98% sensitivity/100% specificity). Fasting serum C-peptide was highly correlated to 90-min serum C-peptide during the test (r = 0.97, P < 0.0001). A fasting serum C-peptide ≥ 0.07 nmol/l was the optimal cut-off (100% sensitivity and 97% specificity) for significant endogenous insulin secretion (defined as 90-min stimulated serum C-peptide ≥ 0.2 nmol/l). CONCLUSIONS: Insulin omission may not always be necessary during a mixed meal tolerance test and fasting serum C-peptide may offer a practical alternative in insulin-treated patients.

Islet autoantibodies can discriminate maturity-onset diabetes of the young (MODY) from Type 1 diabetes.

AIM: Maturity-onset diabetes of the young is a monogenic form of familial, young-onset diabetes. It is rare (∼1% diabetes) and may be misdiagnosed as Type 1 diabetes and inappropriately treated with insulin. Type 1 diabetes is characterized by the presence of islet autoantibodies, including glutamate decarboxylase (GAD) and islet antigen-2 (IA-2) antibodies. The prevalence of islet autoantibodies is unknown in maturity-onset diabetes of the young and may have the potential to differentiate this form of diabetes from Type 1 diabetes. The aim of this study was to determine the prevalence of GAD and IA-2 antibodies in patients with maturity-onset diabetes of the young and Type 1 diabetes. METHODS: We measured plasma GAD and IA-2 antibodies in 508 patients with the most common forms of maturity-onset diabetes of the young (GCK: n = 227; HNF1A: n = 229; HNF4A: n = 52) and 98 patients with newly diagnosed Type 1 diabetes (diagnosed < 6 months). Autoantibodies were considered positive if ≥ 99th centile of 500 adult control subjects. RESULTS: GAD and/or IA-2 antibodies were present in 80/98 (82%) patients with Type 1 diabetes and 5/508 (< 1%) patients with maturity-onset diabetes of the young. In the cohort with Type 1 diabetes, both GAD and IA-2 antibodies were detected in 37.8% of patients, GAD only in 24.5% and IA-2 only in 19.4%. All five patients with maturity-onset diabetes of the young with detectable antibodies had GAD antibodies and none had detectable IA-2 antibodies. CONCLUSION: The prevalence of GAD and IA-2 antibodies in maturity-onset diabetes of the young is the same as in control subjects (< 1%). The finding of islet autoantibodies, especially IA-2 antibodies, makes the diagnosis of maturity-onset diabetes of the young very unlikely and genetic testing should only be performed if other clinical characteristics strongly suggest this form of diabetes rather than Type 1 diabetes. This supports routine islet autoantibody testing before proceeding to more expensive molecular genetic testing.

Urine C-peptide creatinine ratio is an alternative to stimulated serum C-peptide measurement in late-onset, insulin-treated diabetes.

AIMS: Serum C-peptide measurement can assist clinical management of diabetes, but practicalities of collection limit widespread use. Urine C-peptide creatinine ratio may be a non-invasive practical alternative. The stability of C-peptide in urine allows outpatient or community testing. We aimed to assess how urine C-peptide creatinine ratio compared with serum C-peptide measurement during a mixed-meal tolerance test in individuals with late-onset, insulin-treated diabetes. METHODS: We correlated the gold standard of a stimulated serum C-peptide in a mixed-meal tolerance test with fasting and stimulated (mixed-meal tolerance test, standard home meal and largest home meal) urine C-peptide creatinine ratio in 51 subjects with insulin-treated diabetes (diagnosis after age 30 years, median age 66 years, median age at diagnosis 54, 42 with Type 2 diabetes, estimated glomerular filtration rate > 60 ml min(-1) 1.73 m(-2) ). RESULTS: Ninety-minute mixed-meal tolerance test serum C-peptide is correlated with mixed-meal tolerance test-stimulated urine C-peptide creatinine ratio (r = 0.82), urine C-peptide creatinine ratio after a standard breakfast at home (r = 0.73) and urine C-peptide creatinine ratio after largest home meal (r = 0.71). A stimulated (largest home meal) urine C-peptide creatinine ratio cut-off of 0.3 nmol/mmol had a 100% sensitivity and 96% specificity (area under receiver operating characteristic curve = 0.99) in identifying subjects without clinically significant endogenous insulin secretion (mixed-meal tolerance test-stimulated C-peptide < 0.2 nmol/l). In detecting a proposed serum C-peptide threshold for insulin requirement (stimulated serum C-peptide < 0.6 nmol/l), a stimulated (largest home meal) urine C-peptide creatinine ratio cut-off of 0.6 nmol/mmol had a sensitivity and specificity of 92%. CONCLUSION: In patients with insulin-treated diabetes diagnosed after age 30 years, urine C-peptide creatinine ratio is well correlated with serum C-peptide and may provide a practical alternative measure to detect insulin deficiency for use in routine clinical practice.

Thermogenic gas hydrates in the gulf of Mexico.

Thermogenic gas hydrates were recovered from the upper few meters of bottom sediments in the northwestern Gulf of Mexico. The hydrates were associated with oil-stained cores at a water depth of 530 meters. The hydrates apparently occur sporadically in seismic "wipeout" zones of sediments in a region of the Gulf continental slope at least several hundred square kilometers in area.

Faecal calprotectin effectively excludes inflammatory bowel disease in 789 symptomatic young adults with/without alarm symptoms: a prospective UK primary care cohort study.

BACKGROUND: Primary care faecal calprotectin testing distinguishes inflammatory bowel disease (IBD) from functional gut disorder in young patients presenting with abdominal symptoms; however, previous evaluations have excluded patients with alarm symptoms. AIMS: We sought to evaluate the diagnostic accuracy of calprotectin to distinguish IBD from functional gut disorder in young adults in whom general practitioners (GPs) suspected IBD; including patients reporting gastrointestinal alarm symptoms. We hypothesised that calprotectin would reduce secondary care referrals and healthcare costs. METHODS: We undertook a prospective cohort study of 789 young adults (18-46 years old) presenting with gastrointestinal symptoms to 49 local general practices that had undergone calprotectin testing (1053 tests: between Jan 2014 and May 2016) because of suspected IBD. We considered calprotectin levels of ≥100 µg/g positive. Primary and secondary care records over 12 months from the point of calprotectin testing were used as the reference standard. RESULTS: Overall, 39% (308/789) patients reported gastrointestinal alarm symptoms and 6% (50/789) tested patients were diagnosed with IBD. The positive and negative predictive values of calprotectin testing for distinguishing IBD from functional gut disorder in patients with gastrointestinal alarm symptoms were 50% (95% CI 36%-64%) and 98% (96%-100%): and in patients without gastrointestinal alarm symptoms were 27% (16%-41%) and 99% (98%-100%), respectively. We estimate savings of 279 referrals and £160 per patient. CONCLUSIONS: Calprotectin testing of young adults with suspected IBD in primary care accurately distinguishes IBD from functional gut disorder, even in patients with gastrointestinal alarm symptoms and reduces secondary care referrals and diagnostic healthcare costs.

The IGF axis in baboon pregnancy: placental and systemic responses to feeding 70% global ad libitum diet.

Information on the influence of poor maternal nutrition on the regulation of responses to pregnancy, placental and fetal growth and development is critical to a better understanding of pregnancy physiology and pathophysiology. We determined normal changes and effects of controlled and monitored moderate nutrient restriction (NR) (global nutrient intake reduced to 70% of food consumed by mothers feeding ad libitum from 0.16 to 0.5 of gestation) in the baboon, on important hematological, biochemical, and hormonal indices of fetal growth and placental function. Serum IGF-I:IGFBP-3 ratio was lower in pregnant than control non-pregnant baboons feeding ad libitum. Serum concentrations of total and free IGF-I were decreased in NR mothers compared with controls (p<0.05). The decrease in fetal IGF-I did not reach significance (p=0.057). Serum IGF-I: IGFBP-3 ratio was decreased by NR in both mothers and fetuses. Maternal serum IGF-II was unchanged by NR. Placental IGF-I mRNA and protein abundance were similarly reduced whereas IGF-II mRNA increased in placental tissue of NR compared to control mothers. Systemic (maternal) and local (placental) IGFBP-1 and IGFBP-3 mRNA and protein abundance were unchanged by NR. Type 1 IGF receptor protein in the syncytiotrophoblast increased in NR. Type 2 IGF receptor protein was present in the stem villi core, and decreased after NR. We conclude that moderate NR in this important non-human primate model significantly disrupts the maternal and placental IGF-IGFBP axis and influences placental expression of this key system at the gene and protein level. Changes observed appear to be directed toward preserving placental growth.

A pragmatic protocol for I-131 rhTSH-stimulated ablation therapy in patients with renal failure.

PURPOSE: Ablation of thyroid remnants in patients with differentiated thyroid carcinoma and renal failure can be challenging because of the altered and variable clearance rates of iodine from the blood secondary to variations in dialysis protocols, which complicate the selection of the appropriate I-131 dose. The advent of recombinant human TSH allows a simpler approach to dosimetry and ablation without rendering the patient hypothyroid. Avoidance of hypothyroidism may be an important consideration for patients who are experiencing various morbidities from conditions associated with renal failure. METHOD: Three patients on dialysis, who had undergone total thyroidectomy and were euthyroid on L-thyroxine replacement, were given diagnostic doses of I-131 followed by blood and whole-body retention measurements through serial dialyses to determine individual blood clearance rates. After administration of rhTSH, each patient received an ablative dose of I-131 calculated to keep total body dose below 1 Gy. RESULTS: The treatments were administered without complications, and in follow-up imaging of 2 available patients, the ablations were demonstrated to be complete. CONCLUSION: Dosimetry performed on euthyroid dialysis patients permits I-131 dose selection and avoids the additional morbidity of hypothyroidism.

Detection of C-Peptide in Urine as a Measure of Ongoing Beta Cell Function.

C-peptide is a protein secreted by the pancreatic beta cells in equimolar quantities with insulin, following the cleavage of proinsulin into insulin. Measurement of C-peptide is used as a surrogate marker of endogenous insulin secretory capacity. Assessing C-peptide levels can be useful in classifying the subtype of diabetes as well as assessing potential treatment choices in the management of diabetes.Standard measures of C-peptide involve blood samples collected either fasted or, most often, after a fixed stimulus (such as oral glucose, mixed meal, or IV glucagon). Despite the established clinical utility of blood C-peptide measurement, its widespread use is limited. In many instances this is due to perceived practical restrictions associated with sample collection.Urine C-peptide measurement is an attractive noninvasive alternative to blood measures of beta-cell function. Urine C-peptide creatinine ratio measured in a single post stimulated sample has been shown to be a robust, reproducible measure of endogenous C-peptide which is stable for three days at room temperature when collected in boric acid. Modern high sensitivity immunoassay technologies have facilitated measurement of C-peptide down to single picomolar concentrations.

Galanin inhibits insulin secretion and induces hyperglycemia in dogs.

Intravenous administration of galanin into fasted conscious dogs produced a dose-dependent hyperglycemia accompanied by decreases in plasma insulin levels, but with no elevation of plasma glucagon levels. Galanin infusions produced greater parenteral glucose-induced rises in plasma glucose levels along with markedly blunted insulin responses compared with glucose and insulin responses to control glucose infusions. Immediately after cessation of the galanin infusions, elevation of plasma insulin levels occurred in the basal state and after parenteral glucose loading. These results suggest that galanin's hyperglycemic activity is predominantly mediated by a reversible inhibition of insulin secretion.

Glucagon-like peptide I reduces postprandial glycemic excursions in IDDM.

Effects of human glucagon-like peptide I (GLP-I)(7-36)amide were examined in volunteers having insulin-dependent diabetes mellitus (IDDM) with residual C-peptide (CP) secretion (n = 8, 7 men and 1 woman; age, 31 +/- 1.4 years; body mass index, 24.7 +/- 0.7 kg/m2; duration of diabetes, 3.2 +/- 0.8 years; insulin dose, 0.41 +/- 0.05 U.kg-1.day-1; meal-stimulated CP, 1.0 +/- 0.2 nmol/l [means +/- SE]). After a mixed meal (Sustacal, 30 kJ/kg body wt), intravenous injection of GLP-I, 1.2 pmol.kg-1.min-1 through 120 min, virtually abolished increments of plasma glucose, CP, pancreatic polypeptide (PP), and glucagon concentrations, with no significant effect on plasma gastrin levels during the infusions. At reduced dosage (0.75 pmol.kg-1.min-1), GLP-I had lesser effects on plasma glucose and CP levels. On cessation of intravenous GLP-I infusions after the meals, plasma glucose, CP, PP, and glucagon concentrations rebounded toward control levels by 180 min, and the response of plasma gastrin was prolonged. These rebound responses are consistent with intestinal delivery of food retained in the stomach on escape from inhibition of gastric emptying by GLP-I. Infusion of 1.2 pmol.kg-1.min-1 GLP-I with 20 g glucose (10% dextrose in water) injected intravenously over 60 min enhanced plasma responses of immunoreactive CP; the mean incremental areas under concentration curves (0-60 min) increased sixfold, but the glycemic excursion was not affected. Thus, in CP-positive IDDM, pharmacological doses of GLP-I reduce glycemic excursions after meals by a mechanism(s) not dependent on stimulation of insulin secretion, presumably involving delayed gastric emptying.(ABSTRACT TRUNCATED AT 250 WORDS)