Insulin binding to cultured human fibroblasts increases with normal and precocious aging.

Specific and nonspecific [125I]insulin binding and concentration of unlabeled hormone producing 50 percent competition with 1.0 nanomolar [125I]insulin for specific binding sites correlated positively with age of fibroblast donors. Cells from four children with precocious aging--three with progeria and one with Rothmund syndrome-resembled those from the chronologically old.

Growth hormone (GH) insensitivity due to primary GH receptor deficiency.

As demonstrated in Table 2, the differential diagnosis of growth hormone insensitivity (GHI) includes a number of discrete disorders that can be broadly classified as primary or secondary forms. We have selected GHRD (Laron syndrome) as the prototypic disorder of GHI, in part because such dramatic and rapid progress has been made in this clinical condition over the last 6 yr. These advances represent the fortunate convergence of: 1) the cloning of the GHR gene and the identification of deletions and mutations of this gene in GHRD; 2) the development of assay methods for measurement of the GHBP, IGF peptides, and binding proteins; 3) the discovery of a larger number of affected individuals than had been previously suspected, including the recognition and description of a large genetically homogeneous population of GHRD patients in Ecuador; and 4) the production of recombinant IGF-I for therapeutic trials in GHRD. Although we are still in the early phases of clinical trials of recombinant hIGF-I in GHRD, preliminary results have been encouraging. Whether this promise translates into genuine improvements in height and body composition, without significant clinical toxicity, remains to be determined. Similarly, the suitability of IGF-I therapy for other, particularly secondary, forms of GHI is still uncertain, although the responsiveness of GHD-IA patients seems to parallel that seen in GHRD (66, 78). The next few years should provide exciting and potentially important new data on the clinical spectrum, biochemical and molecular characteristics, and responsiveness to therapy of syndromes of GHI.

Insulin-dependent childhood diabetes. Normal viability of cultured fibroblasts.

Cultured skin fibroblasts from clinically normal offspring of two parents with non-insulin-dependent diabetes have demonstrated premature senescence as a decreased ability of cells to establish colonies when inoculated at low density (plating efficiency). The present study tested the hypothesis that there is an inherent cellular defect affecting viability of diabetic cells in insulin-dependent diabetes. Four insulin-dependent patients, aged 12 to 19 years, included two with joint contracture, skin changes, and growth failure; one with thyroiditis and past history of nephrosis; and one with a family history of insulin dependency. Ten control subjects, aged 10 to 52 years, had negative family histories and normal oral glucose tolerance tests. Number of cells per confluent dish correlated significantly with donor age (p less than 0.001) at 30 and 40 in-vitro generations. The patients' cells' mean confluent density did not differ from that of five age-matched controls. Plating efficiency correlated with donor age at 30 in-vitro generations ( p less than 0.001); plating efficiency of cells from the youngsters with diabetes was virtually identical to that of control cells at 20, 30, and 40 generations. In this small series of two subjects with in-vivo growth failure, one with associated autoimmune disease and another with familial insulin-dependent disease, cultured fibroblasts demonstrated normal viability and the hypothesis of a cellular growth defect was not confirmed.

Serum proinsulin in children and adolescents with chemical diabetes.

Proinsulin levels (PLC) in serum were determined after gel filtration on specimens obtained during oral glucose tolerance testing (OGTT) in seven patients with repeated abnormality in OGTT and in a group of seven control subjects matched for age. Fasting and thirty-, sixty-, and 120-minute postglucose venous samples were analyzed for glucose (PG) and immunocreactive insulin (IRI) as well as PLC, PG and IRI mean concentrations were greater at all testing times in the patient population, but the mean IRI/PG was significantly higher in the patients only at fasting. PLC mean levels were higher in the patients but not to a level of significance. Percentage of total IRI atributable to PLC at each time point was identical between the two groups. The apparcent diminished effectiveness of circulating insulin in chemical diabetes cannot be attributed to an abnormal proportion of proinsulin.

Ten-year prognosis of impaired glucose tolerance in siblings of patients with insulin-dependent diabetes.

We traced 105 of 140 siblings of children with insulin-dependent diabetes (IDD) who had had oral glucose tolerance tests (OGTT) 10-12 yr earlier. Siblings with abnormal tests by screening criteria (8.3 mmol/L at 1 h, 7.2 at 2 h, N = 44) included all 6 who subsequently developed IDD after 3 mo to 7 yr (5.7% of entire group, 13.6% of abnormal screenees). The National Diabetes Data Group criterion for children (7.8 mmol/L at 2 h) identified 19 siblings, including 5 of the 6 who later developed IDD (26% of abnormals). Subsequent full 4-h OGTT, including analysis of insulin responses, did not improve predictability for subsequent IDD. Thus, siblings of IDD were identified at high risk (14-26%) or at low risk (0-1%) for subsequent IDD by a simple 2-h OGTT. The prolonged latency in the development of IDD indicates that, among siblings of IDD, this disorder may be already chronic for years by the time of clinical onset.

Age-adjusted analysis of insulin responses during normal and abnormal glucose tolerance tests in children and adolescents.

This report analyzes age-specific glucose (PG) and immunoassayable insulin (IRI) responses during oral glucose tolerance testing (OGTT) and examines test results in children and adolescents with OGTT abnormality using the age-appropriate control data. Controls' (n = 93) and patients' (n = 63) results were compared on the basis of statural age (SA) at the time of testing. Control tests (n = 101) showed significant positive correlation of fasting and four-hour postingestion PG with SA (p less than 0.001), but mean area under the PG curves did not vary between the SA groups (I--18.69 months, II--70-131 months, III--132+ months). The absence of differences of other sampling times permits uniform diagnostic criteria for this age group. IRI was positively correlated with SA at all testing times, and mean levels differed significantly between each SA group at every sampling time; the mean areas under the IRI curve also differed significantly between SA groups as did the mean ratios of IRI area to PG area (group I--0.2639 +/- 0.0175 S.E.M., group II--0.3864 +/- 0.0235, group III--0.6262 +/-0.0491). Patient tests (n = 110) were separated into normal (N), borderline (B), and chemical-diabetic (C) for each SA group. IRI means were above control data for each test type in each SA group at all sampling times; one fourth of these differences were significant. IRI responses also increased within each SA group from N to B to C tests. Mean IRI areas and IRI area to PG are mean ratios were higher than in controls, and this difference was greatest with the most abnormal (C) test type in each SA group. A subgroup of three patients who had low IRI responses from the outset and developed overt diabetes in one to three years was excluded from the analysis. In contrast to apparent relative insulin inefficiency with normal maturation and with chemical diabetes, they had exceptional responsiveness to their low IRI levels. Variable involvement of alpha as well as beta cells in the pathophysiology of diabetes is suggested as one explanation for these paradoxic observations. Changing receptor affinity might also be implicated.

Islet cell and other organ-specific antibodies in U.S. Caucasians and Blacks with insulin-dependent diabetes mellitus.

Islet cell antibodies (ICA) were detected in 168 (33%) of 504 patients with insulin-dependent diabetes mellitus (IDDM). Mean age of onset of IDDM was 8.6 +/- 0.2 yr and mean age at testing was 13.4 +/- 0.3 yr. None of 162 controls without diabetes (mean age 21.8 +/- 0.9 yr) had ICA. Caucasian patients (404) had a 74% frequency of ICA within 3 mo of diagnosis and an overall ICA frequency of 36%. These results were similar to those reported from Europe. Black patients (100) had lower frequencies of ICA (P < 0.01) and thyroid antibodies (P < 0.05). Caucasian patients with onset of IDDM before 5 yr of age (107) had a lower frequency (P < 0.01) of ICA (21%) than those (297) with a later age of onset (42%). Patients with persistent ICA beyond 5 yr of IDDM had increased frequencies of gastric parietal and adrenal cortex cell antibodies. Thyroid microsomal antibodies were less frequent (P < 0.05) in blacks (4%) than in Caucasians (20%). The former did not have adrenal antibodies. Similar ICA frequencies among Caucasians with IDDM in the U.S. and in Europe suggest that etiologic factors are similar in the two geographic regions. The lower frequencies of ICA in patients with IDDM onset before 5 yr of age suggest that some of these patients may have a different etiology and/or a more rapid disappearance of islet cell antigens than patients with a later onset.l The lower ICA frequencies in black patients can be explained by heterogeneity of IDDM in this group and by admixture of IDDM susceptibility genes from the Caucasian genome to the black genome.

Diminution of bone mass in childhood diabetes.

Photon absorption measurements of forearm bone density in 196 insulin-dependent patients, age 6--26 years, were compared with findings in 124 controls. Expected density, gm. Ca/cm.2 bone width (M/W), was calculated from regressions of M/W on ulnar length for white and black male and female controls. There were no significant correlations between M/W differences from expected and serum Ca, Mg, P, or alkaline phosphatase levels, estimated physical activity level, insulin dosage, or the presence of joint contracture. White females averaged 8.2 per cent (+/- 1 S.E.M.) loss of M/W, as against white male average loss of 4.7 per cent +/- 1 and black female loss of 2 per cent +/- 2 (p less than 0.001); the black male population was too small for separate analysis. M/W loss greater than 10 per cent was seen in 29 per cent of white males, 19 per cent of blacks, and 48 per cent of white females (p less than 0.02). When the groups were further divided into those with duration of diabetes less than or equal to five years and those with duration greater than five years, significant reduction in M/W average loss over time was seen with white females (10.6 per cent +/- 1.2 to 3.7 per cent+/- 1.5, p less than 0.0001). Expression of this defect in bone mineralization is controlled by race and sex acting independently of each other.

Lessons from the genetics of laron syndrome.

In the decade since the cloning and sequencing of the growth hormone receptor (GHR) and the recognition that the circulating GH-binding protein (GHBP) is structurally identical to the extracellular domain of the GHR, 34 mutations have been described. These include one deletion, eight nonsense mutations, eleven missense mutations, four frameshift mutations and ten splice mutations. More than half of the 131 patients with Laron syndrome whose molecular defects have been identified comprise the Ecuadorian cohort who share a single splice mutation. Variable expression of different homozygous or compound heterozygous defects of the GHR is no greater than the variation within a genetically homogeneous population. Some features, such as birth size and intelligence, are unlikely to be affected by GHRD. Greater understanding of the genetics, physiology, and clinical expression of abnormalities in the GH-GHR-IGF-I (insulin-like growth factor I) axis necessitates a reconsideration of the classification of GH insensitivity (GHI).

Growth in growth hormone insensitivity.

Primary GH insensitivity due to GH receptor deficiency (GHRD) provides a model for studying the discrete effects of severe IGF-I deficiency on growth and body composition. Growth failure in utero is doubtful, but postpartum growth proceeds at rates that result in adult statures 4-12 standard deviations (SDs) below the normal mean. Wide variability in statural effect, even in a genetically homogeneous population, is partly explained by correlation of SD score with biochemical measures of GH effect (IGF-I, IGF-II, and IGFBP-3). Growth and changes in body composition (decreased fat/lean) in patients with GHRD in response to exogenous IGF-I indicate that direct local effects of GH are not necessary for these responses.

Need for residential treatment for children with diabetes mellitus.

Specialists in childhood diabetes in North America were queried about the need for residential facilities for their patients with recurrent hospitalizations and school deficits due to family coping problems. Of 132 respondents, 115 indicated a need for 5-12% of their patients, a total of 530, close to the estimate of 600 based on the number of places available for Danish, Dutch, and German children.

Intracerebral crises during treatment of diabetic ketoacidosis.

Sixty-nine instances of intracerebral complications of diabetic ketoacidosis (DKA), including 29 unpublished occurrences, were analyzed to determine predictive factors, the frequency of other disorders resembling cerebral edema, the effectiveness of intervention to reduce intracranial pressure, and whether any etiologic considerations appeared valid. The review failed to implicate rate of hydration, tonicity of administered fluids, rate of correction of glycemia, or use of bicarbonate. Infants and young children (less than 5 yr of age) were disproportionately represented (33%), as were new-onset patients (62%). Approximately 20% of patients were found to have localized basilar edema, hemorrhage, thromboses, or infection by computed tomography scan or on postmortem examination. The histories of 50% of the patients suggested a period of dramatic neurological change preceding respiratory arrest (RA) during which intervention might be effective. Twenty-three patients were treated for increased intracranial pressure before RA; 13 patients survived in an independent functional state, and 3 survived in a severely disabled or vegetative state. Only 3 of the remaining 46 patients survived normally: 2 were untreated and never developed RA, and 1 was given mannitol at the onset of apnea. This review supports close neurological monitoring and intervention to reduce intracranial pressure when there are definite signs of neurological compromise. However, treatment appears to be successful in only 50% of patients who give sufficient warning for such intervention, and they comprised half of the study population. Therefore, prevention of DKA remains the most important goal to avoid intracerebral complications.

The development of insulin-dependent diabetes mellitus among relatives.

Relatives of patients with insulin-dependent diabetes mellitus (IDDM) carry an increased risk of developing IDDM. A number of studies that focus on the development of IDDM in such relatives, and the metabolic, immunologic, and viral factors involved are reviewed. These studies indicate that the destructive process in the beta-cells goes on for varying and often extended periods before the development of clinical disease. Thus, the events surrounding the time of clinical diagnosis may be of importance only as triggering mechanisms. Future studies may, therefore, be better directed toward long-term surveillance of the metabolic, viral, and immunologic status of first-degree relatives of IDDM subjects and the associations of these factors with genetic influences such as HLA-DR types or subtypes.

Ambulatory diabetes management by a pulse of subcutaneous insulin delivered by a portable pump: preliminary report.

Two teenage patients, who had severe psychosocial problems that complicated their diabetes management, were treated for one month (14-year-old girl) and two months (16-year-old boy) by frequent pulses of insulin injected subcutaneously by a portable, programmed pump. Additional pulses were manually adjusted by the patient before eating. Both patients experienced improved sense of well-being, marked reduction in urine volume and in glycosuria, and reduced glycemic excursions and average levels. The boy had accelerated linear growth and a decreas in HbA1 percentage. Despite marked clinical improvement, permitting return to school, the girl was impelled to interrupt pump administration after two weeks. Both patients continue to use the device voluntarily; a smaller unit, however, that doesn't have the conspicuous external controls, would likely be readily acceptable to most young patients.

Stability of reacted reagent strips (Chemstrips) for blood glucose determinations.

Reacted Chemstrips were placed in an unsealed envelope or in desiccator vials which were opened daily after 1, 2, 3, 4, 5, 6, 7, and 14 days. The time of change of the reading for 2 days in a row by all three observers was noted. Readings in the low and normal range were most stable and can be considered reliable for 2-3 days when protected from light. If in a desiccator tube, the strips can be reliably reread when the tube is opened as long as 7 days later. In a separate study, strips were left exposed on the laboratory bench or placed in a vial and read frequently for 6 h and again at 28 h. This exposure, comparable to the CS being taped to a hospital record, results in reading changes as early as 2 h after reaction.

Emerging epidemic of type 2 diabetes in youth.

This review considers the epidemiologic evidence of an increasing incidence of type 2 diabetes in youth, the classification and diagnostic issues related to diabetes in young populations, pathophysiologic mechanisms relevant to the increasing incidence, the role of genetics and environment, and the community challenge for prevention and treatment. Type 2 diabetes in youth has been recognized to be frequent in populations of native North Americans and to comprise some 30 percent of new cases of diabetes in the 2nd decade of life, largely accounted for by minority populations and associated with obesity. Among Japanese schoolchildren, type 2 diabetes is seven times more common than type 1, and its incidence has increased more than 30-fold over the past 20 years, concomitant with changing food patterns and increasing obesity rates. The forms of diabetes seen in children and youth include typical type 1, occurring in all races; type 2, seen predominantly in minority youth; atypical diabetes, seen as an autosomal dominantly transmitted disorder in African-American populations; and maturity-onset diabetes of the young (MODY), seen rarely and only in Caucasians. Of the nonautoimmune forms of diabetes seen in youth, only type 2 diabetes is increasing in incidence. Proper classification requires consideration of onset (acute/severe versus insidious), ethnicity, family history, presence of obesity, and if necessary, studies of diabetes related autoimmunity. Insulin resistance predicts the development of diabetes in Pima Indians, in offspring of parents with type 2 diabetes, and in other high-risk populations. African-American children and youth have greater insulin responses during glucose tolerance testing and during hyperglycemic clamp study than do whites. There is also evidence of altered beta-cell function preceding the development of hyperglycemia. Of particular interest is the evidence that abnormal fetal and infantile nutrition is associated with the development of type 2 diabetes in adulthood. The thrifty phenotype hypothesis states that poor nutrition in fetal and infant life is detrimental to the development and function of the beta-cells and insulin sensitive tissues, leading to insulin resistance under the stress of obesity. The thrifty genotype hypothesis proposes that defective insulin action in utero results in decreased fetal growth as a conservation mechanism, but at the cost of obesity-induced diabetes in later childhood or adulthood. The vast majority of type 2 diabetes in adults is polygenic and associated with obesity. Monogenic forms (MODY, maternally transmitted mitochondrial mutations) are rare, but are more likely to appear in childhood. Linkage studies of the common polygenic type 2 diabetes have emphasized the heterogeneity of the disorder. The prevention and treatment of type 2 diabetes in children and youth is a daunting challenge because of the enormous behavioral influence, difficulty in reversing obesity, and typical nonadherence in this age-group. The emerging epidemic of type 2 diabetes in the pediatric population, especially among minorities whose proportion in the U.S. population is increasing, presents a serious public health problem. The full effect of this epidemic will be felt as these children become adults and develop the long-term complications of diabetes.

Accuracy of two systems for blood glucose monitoring without a meter (Chemstrip/Visidex).

Blood specimens collected from 159 campers were tested using Visidex (VD) (Ames Company, Elkhart, Indiana) and Chemstrip (CS) (Bio-Dynamics, Boehringer Mannheim, Indianapolis, Indiana) compared with glucose analyzer (GA) results. Readers were physicians, two with no prior experience using either strip and two with some experience using CS. Subsequently, 30 clinic patients and 4 staff contributed random specimens that were read by a trained novice as 68 discrete samples and compared with GA results. In both studies readers did not place blood on the strips and were thus blinded as to source and the possible previous reading with the other strip. Correlations of VD and CS with GA for camp and clinic data were calculated. Data were compared for reliability and errors greater than 20% of reference values (GA) were compared for VD and CS. CS correlated better with GA than did VD estimates. Reliability was also significantly greater for CS than for VD readings. Both of these visually read methods provided clinically useful estimates of glycemia.

Limited joint mobility in childhood diabetes: family studies.

We examined 204 persons with insulin-dependent diabetes mellitus (IDDM), aged 7-23 yr, and 336 of their first-degree relatives, to determine whether there is a genetic component to the development of limited joint mobility. Simple and multiplex pedigrees with IDDM were studied along with normal controls. Only 1 of 90 normal controls had joint stiffness. Among 225 nondiabetic parents of children with IDDM, 7 (3%) had joint limitation, compared with 42 (21%) of children and youth with IDDM. Only 1 of 108 nondiabetic siblings of diabetic probands had limitation. Three parents had adult-onset diabetes and all had limited joint mobility. None of the 8 nondiabetic relatives with joint limitation had diabetic probands with joint involvement; 5 of these 8 tested were negative for islet cell auto-antibodies. There were 11 IDDM multiplex families with at least one member having joint limitation. The concordance rate for limited joint mobility of persons with diabetes for more than 5 yr who were over 12 yr of age was 56%, not different from the 48% frequency in patients with IDDM who met these age and duration criteria. Thus, evidence that limited joint mobility is a metabolic consequence of diabetes includes the virtual absence of limitation among first-degree relatives of probands, including probands with joint stiffness, and that the frequency of joint involvement is not increased in first-degree relatives of patients with IDDM. Furthermore, two brothers with pancreatic hypoplasia and a non-HLA-associated form of IDDM were affected with limited joint mobility. Nonetheless, the expression of this complication must be influenced by host factors, since not all persons with IDDM develop it, and those who do have variable ages of onset without correlation to control measures.

Bone mineral, histomorphometry, and body composition in adults with growth hormone receptor deficiency.

Growth hormone (GH) and insulin-like growth factor I (IGF-I) deficiencies have been associated with osteopenia in both children and adults. To examine the effects of growth hormone resistance on bone mineral and body composition, we studied 11 adults (mean age 30 years) with growth hormone receptor deficiency (GHRD, Laron syndrome) and 11 age- and gender-matched controls from Southern Ecuador. Bone mineral and body composition were determined by dual-energy X-ray absorptiometry. Bone physiology was assessed with biochemical markers of bone turnover and dynamic bone histomorphometry. Bone size and body composition differed markedly between subjects with GHRD and controls. Affected adults were 40 cm shorter than controls, had significantly less lean body mass, and had increased percent body fat. Bone mineral content and density (BMD) at the spine, femoral neck, and whole body were significantly lower in adults with GHRD than in controls. Mean BMD Z scores were -1.5 to -1.6 at all sites in affected women and -2.2 to -2.3 in men with GHRD. Estimated volumetric bone density (BMAD) at the spine and femoral neck, however, was not reduced in GHRD. Spine BMAD was 0.210 +/- 0.025 versus 0.177 +/- 0.021 for affected women versus controls (p < 0.05) and 0.173 +/- 0.018 versus 0.191 +/- 0.025 for men with GHRD versus normals (p = 0.31). Urinary pyridinoline concentrations were significantly greater in adults with GHRD than in controls, while type I collagen C-telopeptide breakdown products and markers of bone formation did not differ. Differences in histomorphometry were limited to a reduction in trabecular connectivity; bone volume and formation rate were similar to controls. These data confirm the importance of the GH/IGF axis in regulating bone size and body composition. The contribution of these peptides to the acquisition and maintenance of bone mineral is less certain since volumetric bone density was preserved despite low levels of IGF-I and IGFBP-3 associated with GH resistance.

Normal insulin binding to cultured fibroblasts from patients with lipoatrophic diabetes.

Confluent fibroblasts were assayed for insulin binding to determine whether there was an inherent abnormality in receptor function to explain the insulin resistance of lipoatrophic diabetes (LD). Cells from three patients and four controls were compared for confluent density, receptor saturation, specific and non-specific binding and the concentration of unlabelled hormone producing 50% competition for binding with labelled ligand. Cells from patients with LD did not differ significantly in any of these characteristics from the controls. These findings indicate that there is not a basic defect in insulin receptors of LD patients. A secondary disruption of binding, e.g. by a circulating factor, remains possible.