Ketosis-prone type 2 diabetes in patients of sub-Saharan African origin: clinical pathophysiology and natural history of beta-cell dysfunction and insulin resistance

Gender and neurogenin3 influence the pathogenesis of ketosis-prone diabetes

Ketosis-prone diabetes (KPD) is a phenotypically defined form of diabetes characterized by male predominance and severe insulin deficiency. Neurogenin3 (NGN3) is a proendocrine gene, which is essential for the fate of pancreatic beta cells. Mice lacking ngn3 develop early insulin-deficient diabetes. Thus, we hypothesized that gender and variants in NGN3 could predispose to KPD. We have studied clinical and metabolic parameters according to gender in patients with KPD (n = 152) and common type 2 diabetes (T2DM) (n = 167). We have sequenced NGN3 in KPD patients and screened gene variants in T2DM and controls (n = 232). In KPD, male gender was associated with a more pronounced decrease in beta-cell insulin secretory reserve, assessed by fasting C-peptide [mean (ng/ml) +/- s.d., M: 1.1 +/- 0.6, F: 1.5 +/- 0.9; p = 0.02] and glucagon-stimulated C-peptide [mean (ng/ml) +/- s.d., M: 2.2 +/- 1.1, F: 3.1 +/- 1.7; p = 0.03]. The rare affected females were in an anovulatory state. We found two new variants in the promoter [-3812T/C (af: 2%) and -3642T/C (af: 1%)], two new coding variants [S171T (af: 1%) and A185S (af: 1%)] and the variant already described [S199F (af: 69%)]. These variants were not associated with diabetes. Clinical investigation revealed an association between 199F and hyperglycaemia assessed by glycated haemoglobin [HbA1c (%, +/-s.d.) S199: 12.6 +/- 1.6, S199F: 12.4 +/- 1.4 and 199F: 14.1 +/- 2.2; p = 0.01]. In vitro, the P171T, A185S and S199F variants did not reveal major functional alteration in the activation of NGN3 target genes. In conclusion, male gender, anovulatory state in females and NGN3 variations may influence the pathogenesis of KPD in West Africans. This has therapeutic implications for potential tailored pharmacological intervention in this population.

The association of the PAX4 gene with type 1 diabetes in Han Chinese

AIMS

In present study, we aimed to evaluate whether the paired box gene 4 (PAX4) may play a role in the pathogenesis of type 1 diabetes (T1D) in Chinese Han population.

METHODS

One hundred and thirty-four cases with T1D and 324 non-diabetic control subjects were selected randomly from Han Chinese. Three tag single nucleotide polymorphisms (SNPs, rs712701, rs2233580, rs2233575) according to HapMap data were selected to analyze. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to genotype.

RESULTS

No difference was found in genotype or allele frequencies between patients and non-diabetic controls in all three SNPs. No difference was found in common haplotypes constructed by these three SNPs, either. For the SNP rs2233575, in non-diabetic controls, the carriers with AA and GA genotypes had lower plasma insulin level than the subjects with GG genotype (P=0.048).

CONCLUSIONS

The present study identified that the PAX4 gene was not associated with the risk of T1D in a Han Chinese sample, suggesting that it is unlikely to have a major effect on the susceptibility to T1D in this population. This is the first study on the PAX4 gene in a Chinese population.

Thirty years of personal experience in hyperglycemic crises: diabetic ketoacidosis and hyperglycemic hyperosmolar state

CONTEXT

Diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS) cause major morbidity and significant mortality in patients with diabetes mellitus. For more than 30 yr, our group, in a series of prospective, randomized clinical studies, has investigated the pathogenesis and evolving strategies of the treatment of hyperglycemic crises. This paper summarizes the results of these prospective studies on the management and pathophysiology of DKA.

SETTING

Our earliest studies evaluated the comparative efficacy of low-dose vs. pharmacological amounts of insulin and the use of low-dose therapy by various routes in adults and later in children. Subsequent studies evaluated phosphate and bicarbonate therapy, lipid metabolism, ketosis-prone type 2 patients, and use of rapid-acting insulin analogs as well as leptin status, cardiac risk factors, proinflammatory cytokines, and the mechanism of activation of T lymphocytes in hyperglycemic crises.

MAIN OUTCOME

The information garnered from these studies resulted in the creation of the 2001 American Diabetes Association (ADA) technical review on DKA and HHS as well as the ADA Position and Consensus Paper on the therapy for hyperglycemic crises.

CONCLUSIONS

Areas of future research include prospective randomized studies to do the following: 1) establish the efficacy of bicarbonate therapy in DKA for a pH less than 6.9; 2) establish the need for a bolus insulin dose in the initial therapy of DKA; 3) determine the pathophysiological mechanisms for the absence of ketosis in HHS; 4) investigate the reasons for elevated proinflammatory cytokines and cardiovascular risk factors; and 5) evaluate the efficacy and cost benefit of using sc regular insulin vs. more expensive insulin analogs on the general ward for the treatment of DKA.

Syndromes of ketosis-prone diabetes mellitus

Ketosis-prone diabetes (KPD) is a widespread, emerging, heterogeneous syndrome characterized by patients who present with diabetic ketoacidosis or unprovoked ketosis but do not necessarily have the typical phenotype of autoimmune type 1 diabetes. Multiple, severe forms of beta-cell dysfunction appear to underlie the pathophysiology of KPD. Until recently, the syndrome has lacked an accurate, clinically relevant and etiologically useful classification scheme. We have utilized a large, longitudinally followed, heterogeneous, multiethnic cohort of KPD patients to identify four clinically and pathophysiologically distinct subgroups that are separable by the presence or absence of beta-cell autoimmunity and the presence or absence of beta-cell functional reserve. The resulting "Abeta" classification system of KPD has proven to be highly accurate and predictive of such clinically important outcomes as glycemic control and insulin dependence, as well as an aid to biochemical and molecular investigations into novel causes of beta-cell dysfunction. In this review, we describe the current state of knowledge in regard to the natural history, pathophysiology, and treatment of the subgroups of KPD, with an emphasis on recent advances in understanding their immunological and genetic bases.

[Heterogeneity of type 1 diabetes mellitus]

Type 1 diabetes (T1D) comprises all forms of autoimmune-mediated and idiopathic beta-cell destruction leading to absolute insulin deficiency. The etiological heterogeneity of T1D has been recognized for the last decades, but it has been divided into only two subtypes so far: autoimmune (T1D)A and non-autoimmune (T1D)B mediated. Polygenic T1DA (isolated or associated to other autoimmune diseases) is the most prevalent type of T1D. T1DA might be part of rare monogenic syndromes related to mutations in the autoimmune regulator gene (AIRE) and FOXp3. Non-autoimmune forms of T1D correspond to approximately 4 to 7% of newly diagnosed T1D and include T1DB, as well as other types of atypical diabetes, for example fulminant type 1 diabetes and adult ketosis-prone diabetes. A new expression of diabetes in young with insulin resistance and obesity, along with the presence of pancreatic autoimmunity markers, namely auto-antibodies to islet cell antigens, is called double diabetes (DD), T1DA plus type 2 diabetes. Evidence has been collected concerning the potential effect of obesity-linked cytokines in amplifying the autoimmune response in DD. Therefore all these issues are presented and discussed in this review as the concept of heterogeneity of Type 1 Diabetes.

Impact of a multidisciplinary intervention for diabetes in Eritrea

BACKGROUND

When hemoglobin A1c (HbA1c) testing was made available to diabetic patients in the nation of Eritrea, the majority of values were markedly increased. As a result, a multidisciplinary clinical education program was instituted in Eritrea and the rate of HbA1c testing was increased to monitor progress.

METHODS

In February 2003, a cooperative diabetes project was initiated in Eritrea to train diabetes educators, enhance physician education, create patient-teaching materials, and promote glucose monitoring. Two additional visits were made in 2003 and 2004. HbA1c values from January 2003 to November 2004 (n = 3606) were reviewed to assess diabetic control for the population and for a subset of individual patients (n = 350). A cohort of 209 diabetic persons were evaluated for demographics, treatment, and prevalence of complications.

RESULTS

The cohort of 209 patients was 34% female and had a mean (SD) age of 50.5 (15.5) years and diabetes duration of 8.6 (6.3) years. Prevalence of hypertension was 37% and proteinuria 6%. For diabetes treatment, 59% received insulin therapy, 35% received oral agents, and 6% received nonpharmacologic treatment. HbA1c values improved significantly between the 1st 6 months of 2003 (median 10.9%) and the last 6 months of 2004 (median 8.5%; P <0.001). Individual patients in whom 2 HbA1c values were measured > or =3 months apart showed a significant mean decrease of 0.5% (P <0.001).

CONCLUSIONS

Our experience suggests that the combination of sustainable upgraded laboratory services and training in clinical management leads to sustainable improvement in diabetes care in developing countries.

[Ketosis-prone atypical diabetes mellitus: report of two cases]

An atypical presentation of diabetes mellitus was described in black subjects, initially in adolescents by Winter et al. then, in adult populations. The principal characteristics of "African" diabetes are an acute onset with severe hyperglycemia and ketosis, and a clinical course of type 2 diabetes mellitus. In the subsequent clinical course after initiation of insulin therapy, prolonged remission is often possible with cessation of insulin therapy and maintenance of appropriate metabolic control. In the subsequent clinical course after initiation of insulin therapy, prolonged remission is often possible with cessation of insulin therapy and maintenance of appropriate metabolic control. The molecular mechanisms underlining the insulin secretory dysfunction are still to be understood and may involve glucolipotoxicity processes. The HLA alleles associated with susceptibility to type 1 diabetes were reported of high frequency in some populations with this form of diabetes, in the absence of makers of pancreatic beta cell autoimmunity. The aim of the present review is to discuss two cases of African diabetes and review the specific diagnostic, metabolic, pathogenic and management features of this atypical diabetes.

Ketosis-prone type 2 diabetes: effect of hyperglycemia on beta-cell function and skeletal muscle insulin signaling

OBJECTIVE

To determine the underlying mechanism for the severe and transient beta-cell dysfunction and impaired insulin action in obese African American patients with ketosis-prone diabetes.

METHODS

The effect of sustained hyperglycemia (glucotoxicity) and increased free fatty acids (lipotoxicity) on beta-cell function was assessed by changes in insulin secretion during a 20-hour glucose (200 mg/m2 per minute) and a 48-hour Intralipid (40 mL/h) infusion, respectively. Insulin-activated signaling pathways and pattern of Akt-1 and Akt-2 expression and insulin-stimulated phosphorylation were analyzed in skeletal muscle biopsy specimens. Studies were performed in an obese African American woman within 48 hours after resolution of diabetic ketoacidosis and 1 week after discontinuation of insulin treatment.

RESULTS

Dextrose infusion rapidly increased C-peptide levels from a baseline of 3.2 ng/mL to a mean of 7.1 +/- 0.5 ng/mL during the first 8 hours of infusion; thereafter, C-peptide levels progressively declined. Lipid infusion was not associated with any deleterious effect on insulin and C-peptide secretion. Initial in vitro stimulation of muscle tissue with insulin resulted in a substantial and selectively decreased Akt-2 expression and insulin-stimulated phosphorylation on the serine residue. Improved metabolic control resulted in 70% greater Akt expression at near-normoglycemic remission in comparison with the period of hyperglycemia.

CONCLUSION

Hyperglycemia, but not increased free fatty acid levels, led to progressive beta-cell dysfunction and impaired insulin secretion. Hyperglycemia was also associated with diminished skeletal muscle Akt expression and phosphorylation in an African American woman with ketosis-prone diabetes, and this defect improved notably with aggressive insulin therapy. These results indicate the importance of glucose toxicity in the pathogenesis of ketosis-prone diabetes in obese African American patients.

Relato de caso: diabetes Flatbush - da cetoacidose ao tratamento não-farmacológico

Um subgrupo de pacientes, em sua maioria negros ou hispânicos e obesos, tem a cetoacidose diabética (CAD) como forma de apresentação de diabetes mellitus (DM), mas, devido à sua evolução clínica, posteriormente é classificado como DM tipo 2. Estes indivíduos têm pesquisa de auto-anticorpos anti-GAD, anti-IA2 e anti-insulina negativa, mas freqüentemente em associação com HLA classe II de risco para DM tipo 1 (DRB1*03 e/ou DRB1*04). Este subtipo peculiar de DM é denominado diabetes flatbush. Neste artigo, relatamos o caso de uma paciente de origem caucasiana com tais características, na qual foi possível retirada da insulinoterapia. Os possíveis fatores associados a esta evolução favorável serão discutidos.

Hyperglycemic crises in diabetes mellitus: diabetic ketoacidosis and hyperglycemic hyperosmolar state

Diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS) potentially are fatal but largely preventable acute metabolic conditions of uncontrolled diabetes, the incidence of which continues to increase. Mortality from DKA has declined remarkably over the years because of better understanding of its pathophysiology and treatment. The mortality rate of HHS remains alarmingly high, however, owing to older age and mode of presentation of patients and associated comorbid conditions. DKA and HHS also are economically burdensome; therefore, any resources invested in their prevention would be rewarding.

Accuracy and predictive value of classification schemes for ketosis-prone diabetes

OBJECTIVE

Ketosis-prone diabetes (KPD) is an emerging, heterogeneous syndrome. A sound classification scheme for KPD is essential to guide clinical practice and pathophysiologic studies. Four schemes have been used and are based on immunologic criteria, immunologic criteria and insulin requirement, BMI, and immunologic criteria and beta-cell function (Abeta classification). The aim of the present study is to compare the four schemes for accuracy and predictive value in determining whether KPD patients have absent or preserved beta-cell function, which is a strong determinant of long-term insulin dependence and clinical phenotype.

RESEARCH DESIGN AND METHODS

Consecutive patients (n = 294) presenting with diabetic ketoacidosis and followed for 12-60 months were classified according to all four schemes. They were evaluated longitudinally for beta-cell autoimmunity, clinical and biochemical features, beta-cell function, and insulin dependence. beta-Cell function was defined by peak plasma C-peptide response to glucagon >or=1.5 ng/ml. The accuracy of each scheme to predict absent or preserved beta-cell function after 12 months of follow-up was tested using multiple statistical analyses.

RESULTS

The "Abeta" classification scheme was the most accurate overall, with a sensitivity and specificity of 99.4 and 95.9%, respectively, positive and negative likelihood ratios of 24.55 and 0.01, respectively, and an area under the receiver operator characteristic curve of 0.972.

CONCLUSIONS

The Abeta scheme has the highest accuracy and predictive value in classifying KPD patients with regard to clinical outcomes and pathophysiologic subtypes.

Effects of Duration of Type 2 Diabetes Mellitus on Insulin Secretion

OBJECTIVE

To gain insight into the effects of duration of type 2 diabetes on insulin secretion in patients with type 2 diabetes mellitus.

METHODS

C-peptide concentrations were measured every 2 years before and after intravenous injection of 1 mg of glucagon in 89 patients with type 2 diabetes (51 men and 38 women) as part of the Rochester Diabetic Neuropathy Study in those subjects who participated in follow-up (median, 12 years; range, 6 to 14).

RESULTS

Although insulin secretion decreased over time (P<0.001) in the group as a whole, both the pattern and the rate of decline in C-peptide concentration differed considerably among the study subjects. Insulin secretion, whether measured as fasting C-peptide, 6-minute C-peptide, or postglucagon increment in C-peptide concentrations, declined with increasing duration of diabetes in approximately half of the patients but either increased or remained essentially constant over time in the other half. The decrease in insulin secretion was not associated with a deterioration in glycemic control because hemoglobin A1c also declined (P<0.005) during the same interval.

CONCLUSION

We conclude that insulin secretion decreases over time in many patients with type 2 diabetes. Because the rate of decline is variable, the predictive value of any single measurement is limited. These data indicate that although a decrease in insulin secretion over time is characteristic of type 2 diabetes mellitus, it is not inevitable.

Estrogens protect pancreatic beta-cells from apoptosis and prevent insulin-deficient diabetes mellitus in mice

In diabetes, the death of insulin-producing beta-cells by apoptosis leads to insulin deficiency. The lower prevalence of diabetes in females suggests that female sex steroids protect from beta-cell injury. Consistent with this hypothesis, 17beta-estradiol (estradiol) manifests antidiabetic actions in humans and rodents. In addition, estradiol has antiapoptotic actions in cells that are mediated by the estrogen receptor-a (ERalpha), raising the prospect that estradiol antidiabetic function may be due, in part, to a protection of beta-cell apoptosis via ERalpha. To address this question, we have used mice that were rendered estradiol-deficient or estradiol-resistant by targeted disruption of aromatase (ArKO) or ERalpha (alphaERKO) respectively. We show here that in both genders, ArKO(-/-) mice are vulnerable to beta-cell apoptosis and prone to insulin-deficient diabetes after exposure to acute oxidative stress with streptozotocin. In these mice, estradiol treatment rescues streptozotocin-induced beta-cell apoptosis, helps sustain insulin production, and prevents diabetes. In vitro, in mouse pancreatic islets and beta-cells exposed to oxidative stress, estradiol prevents apoptosis and protects insulin secretion. Estradiol protection is partially lost in beta-cells and islets treated with an ERalpha antagonist and in alphaERKO islets. Accordingly, alphaERKO mice are no longer protected by estradiol and display a gender nonspecific susceptibility to oxidative injury, precipitating beta-cell apoptosis and insulin-deficient diabetes. Finally, the predisposition to insulin deficiency can be mimicked in WT mice by pharmacological inhibition of ERalpha by using the antagonist tamoxifen. This study demonstrates that estradiol, acting, at least in part, through ERalpha, protects beta-cells from oxidative injury and prevents diabetes in mice of both genders.

Comparison of type 1, type 2, and atypical ketosis-prone diabetes at 4 years of diabetes duration

CONTEXT

Atypical ketosis-prone diabetes (KPD) is frequently detected in obese individuals at diagnosis of diabetes, yet its precise pathophysiology is not understood.

AIM

The hypothesis tested in this study states that while individuals with atypical KPD are phenotypically similar to those with type 2 diabetes, metabolically, they behave more like individuals with autoimmune type 1 diabetes.

METHODS

Thirty-seven individuals of Black, Hispanic, or White background and a diagnosis of diabetes mellitus for an average duration of 4 years participated in this cross-sectional study. Ten, 12, and 15 subjects had type 1, atypical, and type 2 diabetes, respectively. Insulin secretion was evaluated by a mixed-meal test. Insulin sensitivity and fuel oxidation were assessed by simultaneous euglycemic hyperinsulinemic clamp and indirect calorimetry. Lastly, a 12-h insulin withdrawal test was performed.

RESULTS

Insulin secretion, insulin sensitivity, and the insulin withdrawal tests yielded significant differences for type 1 vs. atypical diabetes and type 1 vs. type 2 diabetes, while there were no significant differences between atypical vs. type 2 diabetes. The indirect calorimetry showed higher-than-normal basal nonprotein respiratory quotients (RQs) and lower-than-normal insulin-stimulated nonprotein RQs across the three study groups.

CONCLUSIONS

After 4 years from diabetes diagnosis and while far from optimal glycemic control, atypical KPD resembles type 2 diabetes phenotypically and metabolically as well. Therefore, this study supports the classification of atypical KPD as ketosis-prone type 2 diabetes, and the concept that metabolic inflexibility occurs in the presence of insulin resistance in type 1 and type 2 diabetes.

The Arg121Trp variant in PAX4 gene is associated with beta-cell dysfunction in Japanese subjects with type 2 diabetes mellitus

Mutations in PAX4, a transcription factor involved in the beta-cell differentiation, could predispose to the development of type 2 diabetes mellitus. To clarify the role of PAX4 Arg121Trp mutation on the development of type 2 diabetes mellitus, we try to determine the clinical phenotype in diabetic subjects with this mutation. Study subjects consisted of 793 type 2 diabetic patients and 318 control subjects. Genotyping for Arg121Trp polymorphism was performed by Invader assay. Clinical phenotype was determined in diabetic subjects including 20 Trp121 carriers and 142 wild-type subjects using a combination of 2-compartment model of C-peptide kinetics and minimal model analysis during intravenous glucose tolerance test. We detected 3 Trp/Trp, 51 Arg/Trp, and 739 Arg/Arg in diabetic subjects, and 16 Arg/Trp and 302 Arg/Arg in control subjects. The frequency of Trp121 allele was 3.59% and 2.51% in diabetic and control groups, respectively (P = .19). Rate of insulin users was higher in Trp121 carriers compared with the wild-type group (42.5% vs 25.0%, P = .0046). First-phase C-peptide secretion was significantly decreased in the diabetic subjects with Trp121 allele compared with the patients with wild type (P = .0048), whereas there were no significant differences in insulin sensitivity and glucose effectiveness between the groups. Arg121Trp mutation in PAX4 gene could be associated with beta-cell dysfunction in Japanese subjects with type 2 diabetes mellitus.

Islet autoimmunity and genetic mutations in Chinese subjects initially thought to have Type 1B diabetes

AIMS

To explore the contribution of islet autoimmunity and genetic mutations in Chinese patients initially thought to have Type 1B diabetes.

METHODS

A group of 33 Chinese patients with newly diagnosed Type 1B diabetes, were identified by the absence of autoantibodies to glutamic acid decarboxylase (GAD), IA-2, insulin, thyroid globulin or thyroid peroxidase, or high-risk HLA-DQ haplotypes. The cohort was further characterized by measurement of autoantibodies to carboxypeptidase H (CPH) and SOX13 using radioligand assays, and testing for genetic mutations associated with MODY3/MODY6 and mitochondrial diabetes. Mutations of HNF-1alpha (MODY3) and neuroD1/beta2 (MODY6) genes were screened using the single-strand conformation polymorphism (SSCP) technique and sequencing. Mitochondrial DNA mutations were analysed with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

Within the cohort, we found one patient with a novel mutation, R321H (CGC-->CAC) in exon 5 of the HNF-1alpha gene, one with ND1 mt3316 G-->A mutation in mitochondrial DNA, five with Ala45Thr polymorphisms in the neuroD1/beta2 gene, and two patients with autoantibodies to SOX13.

CONCLUSIONS

Some of the Chinese patients originally thought to have Type 1B diabetes do have other evidence of islet autoimmunity and genetic mutations involved in the underlying aetiology. This suggests that more rigorous screening for these conditions is needed before classifying subjects as having Type 1B diabetes.

Classification of diabetes in young adults: New concepts for an old disease

As clinicians, we are faced to difficult situations in young diabetic patients. The prevalence of type 2 diabetes increases in these patients due to a rising incidence of obesity. We present two clinical observations which both illustrate the insufficiencies of the present classifications. Modern tools are now available for diagnosis such as anti-GAD65 and IA-2 antibodies, genetic tools to investigate for specific mutations, but quantitative means of beta cell mass are lacking. Clinical examination is still accurate to identify type 1 or type 2 diabetes, MODY and mitochondrial diabetes. Weight curve, lesions of acanthosis nigricans, criteria of metabolic syndrome, history of diabetes are critical factors. This problematic has important consequences in our daily practice: the right choice for rapid and good metabolic control.

Access to care for patients with insulin-requiring diabetes in developing countries: case studies of Mozambique and Zambia

OBJECTIVE

The objective of this study was to assess the barriers to care for patients with insulin-requiring diabetes in Mozambique and Zambia.

RESEARCH DESIGN AND METHODS

We used the Rapid Assessment Protocol for Insulin Access to collect information through interviews, discussions, site visits, and document reviews. Government organizations, health facilities, care givers, and patients were asked about care for people with insulin-requiring diabetes. Between 100 and 200 interviews/discussions per country were undertaken in and around the capital city and the regional capital and in a rural area.

RESULTS

Insulin was present in both countries in sufficient quantities, although the financial burden for health services and patients meant that problems with supply exist. There are problems with quantification of needs and equitable distribution of insulin. Problems with availability of syringes and testing equipment were noted, particularly in Mozambique. This lack of tools and infrastructure for diagnosis and follow-up coupled with low levels of health care worker training and lack of diagnostic reagents resulted in a substantial risk of misdiagnosis or failure to detect diabetes. The estimated prevalence of insulin-requiring diabetes differs more than 10-fold between urban and rural areas in Mozambique and 4-fold between Mozambique and Zambia, suggesting that problems in diagnosis and care result in substantial worsening of prognosis for such patients.

CONCLUSIONS

Insulin is necessary but not sufficient to improve prognosis for diabetic patients. A Rapid Assessment Protocol methodology can be used to define problems in health care delivery for diabetes. Proper care for insulin-requiring diabetes necessitates health systems able to provide trained personnel, medicines in sufficient quantity, and diagnostic and monitoring facilities.

Prevalence and characteristics of type 2 diabetes mellitus in 9-18 year-old children with diabetic ketoacidosis

OBJECTIVE

To estimate the prevalence of type 2 diabetes mellitus (DM2) in 9-18 year-old children with diabetic ketoacidosis (DKA) and to describe the presenting biochemical characteristics and response to standardized DKA treatment.

METHODS

Data were collected from a consecutive sample of 9-18 year-old children presenting with DKA. DKA was defined as hyperglycemia and ketosis with an initial pH <7.3, or bicarbonate <15 mmol/l. Patients were classified as having DM2 if they had negative autoantibody status and normal or elevated fasting C-peptide.

RESULTS

The prevalence of DM2 in patients with DKA was 13.0% (6.1-23.3%). There was no significant difference in the presenting pH (7.14 vs 7.15), but blood glucose was higher (735 vs 587 mg/dl) in patients with DM2, than in patients with type 1 DM (DM1). The duration of insulin infusion until resolution of acidosis (17.3 vs 13.2 h) and intensive care unit stay (2.4 vs 1.6 days) were longer in patients with DM2. Seven of the nine patients with DM2 did not require insulin at 1-year follow-up.

CONCLUSIONS

Children with DM2 can present with DKA and constitute a significant percentage in the above 9-year age group. The need for insulin must be carefully re-evaluated as DKA resolves in these patients. Adolescents with DM2 and their families need to be educated about DKA.

High prevalence of glucose-6-phosphate dehydrogenase deficiency without gene mutation suggests a novel genetic mechanism predisposing to ketosis-prone diabetes

CONTEXT

Ketosis-prone diabetes (KPD) is mostly observed in males of West African descent and is characterized by phasic or permanent insulin dependence without apparent autoimmune process.

OBJECTIVE

KPD subjects display a propensity to hyperglycemia-induced acute insulin deficiency, suggesting that they exhibit a propensity to oxidative stress in beta-cells. The enzyme glucose-6-phosphate dehydrogenase (G6PD) is a defense mechanism against oxidative stress, and G6PD deficiency, an X-linked genetic disorder with male predominance, is frequent in West Africans. We hypothesized that mutations in the G6PD gene could predispose to KPD.

DESIGN

We studied G6PD erythrocyte enzyme activity and the insulin secretory reserve (glucagon-stimulated C peptide) in a cohort of hospitalized West Africans with KPD (n = 59) or type 2 diabetes (T2DM; n = 59) and in normoglycemic controls (n = 55). We also studied the G6PD gene in an extended population of KPD patients (n = 100), T2DM patients (n = 59), and controls (n = 85).

RESULTS

The prevalence of G6PD deficiency was higher in KPD than in T2DM and controls (42.3%; 16.9%; 16.4%; P = 0.01). In KPD, but not in T2DM, insulin deficiency was proportional to the decreased G6PD activity (r = 0.33; P = 0.04). We found no increase in the prevalence of G6PD gene mutations in KPD compared with T2DM and controls. Rather, we found a 20.3% prevalence of G6PD deficiency in KPD without gene mutation.

CONCLUSIONS

This study suggests that 1) G6PD deficiency alone is not causative of KPD; and 2) alterations in genes controlling both insulin secretion and G6PD-mediated antioxidant defenses may contribute to the predisposition to KPD in West Africans.

Improved glycemic control in subjects with atypical diabetes results from restored insulin secretion, but not improved insulin sensitivity

African-American subjects often present with hyperglycemic crisis (diabetic ketoacidosis or severe hyperglycemia), yet subsequently are treated without insulin. The pathophysiology of this unique condition is unknown. We hypothesized that recovery from atypical diabetes with intensive insulin therapy resulted from a reversal of a defect in beta-cell function and improved insulin sensitivity. We studied eight newly diagnosed, antibody-negative African-American subjects (age, 34-56 yr) who presented with hyperglycemic crisis. Subjects were studied at baseline after overnight glycemic control and again after 3 wk and 3 months of intensive insulin therapy. Insulin sensitivity (SI) was determined from an insulin-modified, frequently sampled i.v. glucose tolerance test, and insulin secretion was measured as the acute insulin response to glucose and to a glucagon stimulation test. Fructosamine and hemoglobin A1c declined significantly with intensive insulin therapy, and insulin requirements decreased over time. Both acute insulin response to glucose and the C peptide response to glucagon stimulation test improved by 3 wk (P = 0.02 vs. baseline), and improvements were maintained at 3 months (P = 0.02 vs. baseline). In contrast, the SI remained low throughout the study. We demonstrate that improved glycemic control correlates with a remarkable recovery of beta-cell function, but no change in SI.

PAX4 gene variations predispose to ketosis-prone diabetes

Ketosis-prone diabetes (KPD) is a rare form of type 2 diabetes, mostly observed in subjects of west African origin (west Africans and African-Americans), characterized by fulminant and phasic insulin dependence, but lacking markers of autoimmunity observed in type 1 diabetes. PAX4 is a transcription factor essential for the development of insulin-producing pancreatic beta-cells. Recently, a missense mutation (Arg121Trp) of PAX4 has been implicated in early and insulin deficient type 2 diabetes in Japanese subjects. The phenotype similarities between KPD and Japanese carriers of Arg121Trp have prompted us to investigate the role of PAX4 in KPD. We have screened 101 KPD subjects and we have found a new variant in the PAX4 gene (Arg133Trp), specific to the population of west African ancestry, and which predisposes to KPD under a recessive model. Homozygous Arg133Trp PAX4 carriers were found in 4% of subjects with KPD but not in 355 controls or 147 subjects with common type 2 or type 1 diabetes. In vitro, the Arg133Trp variant showed a decreased transcriptional repression of target gene promoters in an alpha-TC1.6 cell line. In addition, one KPD patient was heterozygous for a rare PAX4 variant (Arg37Trp) that was not found in controls and that showed a more severe biochemical phenotype than Arg133Trp. Clinical investigation of the homozygous Arg133Trp carriers and of the Arg37Trp carrier demonstrated a more severe alteration in insulin secretory reserve, during a glucagon-stimulation test, compared to other KPD subjects. Together these data provide the first evidence that ethnic-specific gene variants may contribute to the predisposition to this particular form of diabetes and suggest that KPD, like maturity onset diabetes of the young, is a rare, phenotypically defined but genetically heterogeneous form of type 2 diabetes.