Wolfgang Kerner

Mutations in the Hepatocyte Nuclear Factor-1α Gene in MODY and Early-Onset NIDDM: Evidence for a Mutational Hotspot in Exon 4

We have recently shown that mutations in the gene encoding the transcription factor hepatocyte nuclear factor (HNF)-1α are the cause of one form of maturity-onset diabetes of the young (MODY3). Here, we report the exon-intron organization and partial sequence of the human HNF-1α gene. In addition, we have screened the ten exons and flanking introns of this gene for mutations in a group of 25 unrelated white subjects from Germany who presented with NIDDM before 35 years of age and had a first-degree relative with NIDDM. Mutations were identified in nine of these individuals, suggesting that mutations in the HNF-1α gene are a common cause of diabetes in German subjects with early-onset NIDDM and a family history of diabetes. Thus, screening for mutations in this gene may be indicated in subjects with early-onset NIDDM. Interestingly, three of the nine mutations occurred at the same site in exon 4 with insertion of a C in a polyCtract, centered around codon 290 (designated Pro291fsinsC), thereby resulting in a frameshift during translation and premature termination. Analyses of linked DNA polymorphisms in the HNF-1α gene indicated that the Pro291fsinsC mutation was present on a different haplotype in each subject, implying that the polyC tract represents a mutational hot spot. We have also identified the mutation in the HNF-1α gene in the Jutland pedigree, one of the original MODY pedigrees reported in the literature, as being a T→G substitution in codon 241, resulting in the replacement of a conserved Cys by Gly (C241G). The information on the sequence of the HNF-1α gene and its promoter region will facilitate the search for mutations in other subjects and studies of the role of the gene in determining normal β-cell function.

Incidence of Hypoglycemic Episodes in Diabetic Patients Under Continuous Subcutaneous Insulin Infusion and Intensified Conventional Insulin Treatment: Assessment by Means of Semiambulatory 24-hour Continuous Blood Glucose Monitoring

The incidence and magnitude of hypoglycemia (i.e., blood glucose values < 50 mg/dl) were assessed by continuous blood glucose monitoring over 24 h in 10 insulin-dependent diabetic (IDD) patients treated with continuous subcutaneous insulin infusion (CSII) and 9 IDD patients under intensified conventional treatment (ICT). A newly developed, battery-powered blood glucose monitor was employed. Patients were thus enabled to move freely in the hospital premises. Despite similar quality of previous blood glucose control (HbA1: 8.0 ± 0.05% CSII versus 8.0 ± 0.3% ICT, x¯ ± SEM), the obtained profiles showed better regulation under CSII treatment (mean blood glucose [MBG], 99.6 ± 10.0 versus 133.1 ± 7.4 mg/dl; M-value, 12.3 ± 3.5 versus 26.2 ± 4.1; mean amplitude of glycemic excursion [MAGE], 71.9 ± 8.7 versus 132.9 ± 14.2 mg/dl; CSII versus ICT, x¯ ± SEM). The incidence of blood glucose values < 50 mg/dl was 9/10 patients (CSII) and 5/9 patients (ICT). In both groups, hypoglycemia was most frequent at noon and was related to elevated pre- and postprandial free insulin levels. Patients became aware of hypoglycemia only in 6/23 episodes (CSII) and 6/8 episodes (ICT). Our data indicate that CSII as well as ICT may result in postprandial hyperinsulinemia leading to frequent hypoglycemic episodes of variable length, reassessing the traditional experience of close correlation between aggressive insulin therapy and enhanced hypoglycemic risk.

Low Fecal Elastase 1 Levels Do Not Indicate Exocrine Pancreatic Insufficiency in Type-1 Diabetes Mellitus

Objectives: On the basis of very low fecal elastase 1 and very high fecal fat estimations, it has been claimed that exocrine pancreatic insufficiency is frequent in diabetic patients, and that in up to 40% of the patients, pancreatic enzyme substitution would be indicated. Because this would affect millions of diabetic patients worldwide, we evaluated this suggestion by testing exocrine pancreatic function in type-1 diabetes using the criterion standard of exocrine pancreatic function tests, the secretin-cerulein test (SCT). The results of this test were then compared with those of fecal elastase 1 and fecal fat estimations. Methods: Thirty-three patients with type-1 diabetes mellitus underwent an SCT, a fecal fat estimation, and 2 fecal elastase 1 tests (using both monoclonal and polyclonal antibodies) to evaluate their exocrine pancreatic function. Results: The SCT results were abnormal in 11 of the 33 patients, who showed only mild to moderate exocrine pancreatic insufficiency, and the stimulated lipase secretion was never less than 10% of the level where pancreatic steatorrhea first occurs. The correlation between fecal elastase 1 and SCT showed much lower sensitivity, specificity, and positive and negative predictive values than did the correlation between SCT and fecal fat. Nonpancreatogenic steatorrhea was present in two thirds of the patients and was probably caused by bacterial overgrowth. Conclusions: Neither low fecal elastase 1 nor raised fecal fat levels reliably indicate exocrine pancreatic insufficiency in type-1 diabetes and therefore should not be used as an indicator for expensive pancreatic enzyme substitution.

Studies on the pathogenesis of the dawn phenomenon in insulin-dependent diabetic patients.

To assess the role of hormonal factors in the pathogenesis of the dawn phenomenon, nocturnal (9:00 PM to 9 AM) concentrations of blood glucose, free insulin, and counterregulatory hormones were determined in eight insulin-dependent diabetic patients under feedback-controlled and continuous insulin infusions after previous blood glucose normalization. Under feedback control, mean insulin requirements, necessary for maintenance of euglycemia rose significantly in the early morning (11:00 PM to 3 AM: 8.4 +/- 1.4; 5 AM to 9 AM: 12.6 +/- 1.5 mU/kg/h; P less than 0.01). Mean free-insulin concentrations did not increase simultaneously. Correspondingly, mean insulin-clearance rates under continuous insulin infusion were higher in the morning (11:00 AM to 3 AM: 359 +/- 58; 5 AM to 9 AM: 459 +/- 72 mL/min/m2; P less than 0.05). Increases of insulin clearance rates were most marked (greater than 15%) in patients whose blood glucose rose during continuous insulin administration. Glucagon and norepinephrine concentrations were stable throughout both parts of the study. Cortisol and growth hormone exhibited the known nocturnal rhythms. Epinephrine levels were at the lower limit of detection at night and rose to normal basal concentrations at 9:00 AM. We conclude that increases of insulin clearance rates may be an important factor for the development of the dawn phenomenon while the role of most counter-regulatory hormones is still uncertain.

Differential Effects of Human and Pork Insulin–Induced Hypoglycemia on Neuronal Functions in Humans

Insulin has been found to cross the blood-brain barrier, and insulin receptors have been detected in different structures of the brain. However, the biological significance of insulin acting in the brain remains unclear. Reports of differential awareness of hypoglycemic symptoms during human insulin (Hl)- and pork insulin (Pl)-induced hypoglycemia hint at a modulatory influence of insulin on sensory processing. In a double-blind study, we recorded auditory-evoked potentials (AEPs), indexing neuronal transmission along sensory pathways, in 30 healthy male subjects during a baseline condition and HI- and PI-induced mild hypoglycemia of 2.65 mM. Fifteen subjects were tested after 20 min and another 15 after 50 min of constant hypoglycemia. During hypoglycemia, subjects had to indicate the severity of hypoglycemic symptoms and their current mood. Hypoglycemia increased latencies of the P3 component and reduced amplitudes of the N1, P2, and P3 components. Despite identical blood glucose and serum insulin levels in both sessions, effects of PI-induced hypoglycemia on AEP components were significantly stronger than those of HI-induced hypoglycemia (P < 0.05). Differences between the effects of the insulins were consistently apparent after 20 min of hypoglycemia, indicating a short-term action of these hormones on central nervous system functions. Also, after 20 min, but not after 50 min, of steady-state hypoglycemia, subjects felt more excited during PI than HI infusion (P < 0.05). The results indicate different influences of HI and PI on sensory function during hypoglycemia. These differences, occurring during early hypoglycemia, could contribute to the differential awareness of hypoglycemic warning symptoms during HI- and PI-induced hypoglycemia in diabetic patients.

Evidence for Effects of Insulin on Sensory Processing in Humans

Systemic insulin passes the blood-brain barrier and insulin receptors have been detected in various brain regions. Yet, the biological significance of insulin acting on the brain remains rather unclear. Reports of different awareness of hypoglycemic symptoms during hypoglycemia induced by human insulin (HI) and porcine insulin (PI) suggest a modulatory influence of insulin on sensory processing. In a double-blind, within-subject, crossover comparison, we recorded visual-evoked potentials (VEP) in 30 healthy men during euglycemia and after 20 or 50 min of constant hypoglycemia of 2.66 mM (47.9 mg/dl) induced by HI and PI. Blood glucose and serum insulin levels were identical in both sessions. Hypoglycemia reduced amplitudes of the VEP components P1 and N2 and increased latencies of N1, P1, and N2. However, hypoglycemia-induced changes in VEP amplitudes and latencies were significantly stronger during PI and HI infusion: P1-N2 difference amplitude decreased from (mean ± SE) 11.9 ± 0.9 to 10.7 ± 0.8 μV during HI and from 12.4 ± 0.9 to 8.7 ± 0.7 μV during PI infusion (P < 0.002). P1 latency increased from 112.0 ± 3.2 to 118.8 ± 3.2 ms during HI and from 114.0 ± 3.3 to 126.3 ± 4.6 ms during PI infusion (P < 0.05). Differences between the effects of the insulins were consistently apparent after 20 min of hypoglycemia, which indicates a short-term action of the hormone. The results add to those of a foregoing study demonstrating differential effects of HI- and PI-induced hypoglycemia on auditory evoked potentials. The changes in sensory processing during hypoglycemia, depending on the type of insulin, suggest a direct modulation of these brain functions by insulin.

Prevalence of Diabetes-Associated Autoantibodies in Schoolchildren: The Karlsburg Type 1 Diabetes Risk Study

Abstract: This study attempts to assess the prevalence of diabetes‐associated autoantibodies in a general population in the northeastern part of Germany, with emphasis on autoantibodies against glutamic acid decarboxylase (GADA), protein tyrosine phosphatase (IA‐2A), and insulin (IAA) by radioassays ≥ 98th percentile, and AAbs binding on pancreatic sections (ICA) by immunofluorescence ≥ 10 Juvenile Diabetes Foundation units. From a total of 11,840 schoolchildren tested for all four AAbs, 821 (6.9%) children were positive for single AAbs, whereas 83 (0.7%) had multiple AAbs. If the primary screening were performed by testing GADA/IA‐2A/IAA, 94% of probands with single AAbs and all with multiple AAbs would be identified. The combinations of GADA/IA‐2A, GADA/IAA, and IA‐2A/IAA would identify 97.6, 98.8, and 85.5% of probands with multiple AAbs, respectively. Thus, combined AAb screening in the general population identifies those probands at risk for diabetes.

Trend of antihyperglycaemic therapy and glycaemic control in 184,864 adults with type 1 or 2 diabetes between 2002 and 2014: Analysis of real-life data from the DPV registry from Germany and Austria.

AIMS To analyse time trends of antihyperglycaemic therapy and glycaemic control in adult subjects with type 1, or type 2 diabetes between 2002 and 2014 in Germany/Austria. METHODS 184,864 adults with diabetes (35,144 type 1 diabetes (T1D), 149,720 type 2 diabetes (T2D)) from the DPV-database documented between 2002 and 2014 were included. Regression models were applied for antihyperglycaemic therapy in T2D (non-pharmacological, OADs only, insulin±OADs), insulin therapy in T1D (CT, ICT, CSII) and T2D (BOT, SIT, CT, ICT, CSII), for the use of insulin analogues, and for glycaemic control (HbA1C, severe hypoglycaemia), adjusting for confounders sex, age, and diabetes duration. RESULTS In T1D, CT (2002:19.7%; 2014:16.0%) and ICT (2002:66.8%; 2014:52.4%) decreased, while CSII increased from 13.5% to 31.5%. In T2D, non-pharmacological treatment became less frequent (2002:36.0%, 2014:21.8%), the use of OADs (2002:19.3%, 2014:28.9%) and insulin±OADs (2002:44.6%, 2014:49.4%) increased. BOT increased from 7.9% to 18.9%, SIT decreased from 12.0% to 8.3%. ICT slightly increased (2002:44.0%, 2014:45.3%), CT decreased (2002:35.8%, 2014:27.2%). Insulin analogues were used more frequently in T1D (rapid-acting:2002:46.8%, 2014:84.8%; long-acting:2002:26.0%, 2014:54.8%) and in T2D (rapid-acting:2002:26.0%, 2014:43.5%; long-acting:2002:13.7%, 2014:53.6%). Until 2011, HbA1C increased in T1D and T2D, but then decreased again. High variability in the rate of hypoglycaemia was observed. CONCLUSIONS This observational study indicates an increased use of insulin pumps in T1D. In T2D, non-pharmacological therapy decreased, and insulin therapy, particular as BOT, rose. An increase in the use of rapid- and long-acting insulin analogues was present in both patient-groups. Time trend was less clear in glycaemic control.

Classically conditioned changes of blood glucose level in humans

Procedures of classical conditioning in animals and man have provided evidence that most psychophysiological responses can be acquired by repeated association with previous neutral stimuli. Many animal studies reported on conditioned changes in the blood glucose level; the nature of the conditioned response (CR), hypo- or hyperglycemia, however, seems to vary with experimental procedures. The present study aimed to elicit conditioned blood glucose changes in human subjects. Thirty male volunteers participated in five sessions each. The sessions were separated by 3 days, with identical time course and procedure. The subjects were informed that we wanted to test the effects of insulin or placebo injections on cognitive functioning, and were kept busy with pseudotests. In four sessions, subjects were injected with 0.035 IU/kg body weight of human insulin as the unconditioned stimulus (US), which induced the expected fall in blood glucose level below 50 mg/dl (UR). Injections were accompanied by a specific stimulus compound (conditioned stimulus, CS) in half of the subjects. In the fifth session, the CS was associated with a placebo injection. About half of the subjects showed a change from the baseline level of blood glucose of more than 10 mg/dl, which we would interpret as a conditioned response. Conditioning occurred more often in those subjects who were given a CS compound in addition to the injection, which itself together with the experimental environment may have been a sufficient CS.

20 Years of Pediatric Benchmarking in Germany and Austria: Age-Dependent Analysis of Longitudinal Follow-Up in 63,967 Children and Adolescents with Type 1 Diabetes.

Background To investigate changes in diabetes treatment over the last two decades in three age-groups of children and adolescents with type 1 diabetes (T1D) from Germany and Austria. Methods 63,967 subjects (<18yr) with T1D documented between 1995 and 2014 from the DPV-database were included and stratified according to age (0.5-<6, 6-<12, 12-<18yr). Regression models were applied for insulin regimens (<3 and ≥4 injection time points/day, or continuous subcutaneous insulin infusion (CSII)), use of rapid- and long acting insulin analogues, NPH insulin, and frequency of self-monitoring of blood glucose (SMBG)/day. Models were adjusted for sex, diabetes duration, and migration background. P-value for trend was given. Findings The number of subjects with <3 injection time points/day decreased from 1995 to 2014 to <5% in all age-groups (p<0.0001). Proportion of patients with ≥4 injections/day increased until the early 2000s, and then declined until 2014. This trend was not found in 6-<12yr olds (p = 0.3403). CSII increased in all age-groups (p<0.0001) with the highest increase in children <6 years (from 0.4% to 79.2%), and the lowest increase in 12-<18 year olds (from 1.0% to 38.9%). NPH insulin decreased in all age-groups (p<0.0001). Insulin analogues, especially rapid-acting, became more frequent in all age-groups (p<0.0001), accounting for 78.4% in 2014 for all subjects. The highest use was found in the youngest children (in 2014: 85.6%), the lowest use in 6-<12 year olds (in 2014: 72.9%). The number of SMBG/day increased from 2.2 to 6.4 with a similar rise in all age-groups (p<0.0001). Frequency was highest in subjects <6yr. Conclusions In all age-groups, T1D treatment was intensified over the last 20 years. Age-specific differences in trends were particularly observed in the number of patients on CSII, in the number of patients with 4 or more injections/day, and in the frequency of SMBG/day.