New classification and diagnostic criteria for insulin resistance syndrome

PIK3R1 mutations in individuals with insulin resistance or growth retardation: Case series and in silico functional analysis

AIMS/INTRODUCTION

Phosphatidylinositol 3-kinase (PI3K) plays a key role in insulin signaling, and mutations in PIK3R1, which encodes a regulatory subunit (p85α) of this enzyme, are responsible for SHORT syndrome, which is associated with insulin-resistant diabetes. We here describe four Japanese individuals from three families with SHORT syndrome who harbor either a common or a previously unknown mutation in PIK3R1 as well as provide an in silico functional analysis of the mutant proteins.

MATERIALS AND METHODS

Gene sequencing was performed to identify PIK3R1 mutations. 3D structural analysis of wild-type and mutant p85α proteins was performed by homology modeling, and structural optimization and molecular dynamics simulations confirmed stable trajectories. Docking simulations of p85α with a phosphopeptide were also conducted.

RESULTS

We identified two families with a common mutation (c.1945C>T, p.R649W) and one family with a previously unidentified mutation (c.1957A>T, p.K653*) of PIK3R1. In silico modeling revealed that both mutations impaired binding of p85α to phosphopeptide, with K653* resulting in the loss of amino acids that contribute to such binding. Docking simulations showed a significant loss of docking energy for the R649W mutant compared with the wild-type protein (P = 0.00329).

CONCLUSIONS

The four cases of SHORT syndrome were associated with early-onset diabetes and intrauterine growth retardation, with the identified mutations likely disrupting the binding of p85α to phosphopeptide and thereby impairing insulin signaling. One case uniquely manifested diabetes without insulin resistance, emphasizing the need for further study of the clinical variability of SHORT syndrome, especially with regard to its associated diabetes.

Utility of the C-peptide/insulin molar ratio for distinguishing type A insulin resistance syndrome from type 2 diabetes

OBJECTIVE

Type A insulin resistance syndrome (IRS), characterized by impaired insulin receptor function due to variants of the insulin receptor gene, manifests as severe insulin-resistant diabetes. Differentiation of type A IRS from type 2 diabetes on the basis of hyperinsulinemia can be challenging. Given the association between insulin receptor dysfunction and reduced insulin clearance, we evaluated the potential of the circulating C-peptide reactivity (CPR)/immunoreactive insulin (IRI) molar ratio, a marker of insulin clearance, for distinguishing type A IRS from type 2 diabetes.

METHODS

We retrospectively analyzed CPR and IRI levels measured during a 75-g oral glucose tolerance test (OGTT) in 18 individuals with type A IRS and 126 with type 2 diabetes. Receiver operating characteristic (ROC) curve analysis was performed to determine the diagnostic performance of the CPR/IRI molar ratio and IRI levels.

RESULTS

IRI levels were significantly higher and the CPR/IRI molar ratio significantly lower in individuals with type A IRS compared with those with type 2 diabetes. The area under the ROC curve for the CPR/IRI molar ratio at baseline, 1 hour, and 2 hours after OGTT initiation was 0.997 (sensitivity 100%, specificity 99.2%), 0.999 (sensitivity 100%, specificity 97.6%), and 0.997 (sensitivity 100%, specificity 95.1%), respectively. The CPR/IRI molar ratio demonstrated robust diagnostic performance regardless of body mass index or hyperinsulinemia severity.

CONCLUSIONS

The CPR/IRI molar ratio, both at baseline and during OGTT, exhibited higher sensitivity and specificity than IRI levels alone for distinguishing type A IRS from type 2 diabetes. This ratio may serve as a reliable clinical marker for early and accurate diagnosis of type A IRS.

Insulin resistant diabetes mellitus in a girl with mild Rabson-Mendenhall syndrome: efficacy of sodium glucose co-transporter 2 inhibitor

We report a beneficial effect of a sodium glucose co-transporter 2 (SGLT2) inhibitor in the management of insulin resistant diabetes mellitus (IRDM) in a Japanese girl with mild Rabson-Mendenhall syndrome (RMS). At 10 2/12 years of age, she was referred to us because of glucosuria, and was found to have marked acanthosis nigricans and RMS-like facial features such as proptosis, large ears, full lips, and gingival hypertrophy, but not other clinical features frequently found in RMS. At 11 9/12 years of age, her blood HbA1c level, though it remained ~ 6.5% until then, increased to 7.9% with pubertal development. She was treated with an SGLT2 inhibitor and metformin, which ameliorated overt hyperglycemia in the afternoon and the evening (postprandial time) as well as obvious hypoglycemia in the early morning (before breakfast), and reduced her blood HbA1c to 5.5%. Whole exome sequencing revealed probably disease-causing c.2465 T > C:p.(Leu822Pro) of paternal origin and c.3038C > T:p.(Pro1013Leu) of maternal origin in INSR. These findings imply the usefulness of SGLT2 inhibitor in the treatment of IRDM. It is likely that SGLT2 inhibitor mitigated hyperglycemia by increasing the urine glucose excretion and prevented severe hypoglycemia probably because of attenuated hyperinsulinemia in the absence of overt hyperglycemia.

Conquering diabetes by overcoming psychological barriers and embracing health

Living with chronic conditions like diabetes mellitus (DM) or insulin resistance (IR) requires significant self-management, adding to daily life stressors. This stress, known as diabetes distress, along with health empowerment from proper diet and lifestyle, and motivation to eat healthily, greatly impacts quality of life and disease outcomes. Different patient subgroups (type 1 diabetic (T1DM), type 2 diabetic (T2DM), and insulin resistant (IR) individuals) face these challenges differently. This research aims to compare people with IR and DM to those without, and to compare IR, T1DM and T2DM subgroups on psychological factors. Data was collected via an online questionnaire from 746 participants (average age 37.5 years). Among them, 405 had IR (N = 177) or DM (Type 1: N = 116; Type 2: N = 112), and 341 were controls. Results showed that T2DM individuals scored lower than controls on Identified Regulation, Interoceptive Awareness, and Search for Meaning in Life, while the IR group had higher body-mind disconnection. T1DM individuals experienced the highest emotional distress due to the disease but the lowest distress from regular check-ups compared to T2DM and IR groups. The gradient boosting classification model indicated that IR and T1DM groups are homogeneous, whereas T2DM is heterogeneous, with significant within-group variation in disease experience and management. Despite similarities in daily life challenges, significant differences exist in disease experience among the groups. Individual characteristics of T2DM individuals further diversify their attitudes towards disease management.

Novel PIK3R1 gene mutation associated with SHORT syndrome: a case report of a 15-year-old female

OBJECTIVES

To present the clinical journey and management of a 15-year-old female with SHORT syndrome, highlighting the diagnostic challenges and the novel genetic mutation identified.

CASE PRESENTATION

A 15-year-old Filipino female was initially seen in a dermatology clinic at 9 years old for axillary skin darkening, indicative of acanthosis nigricans. Early evaluations revealed elevated blood glucose levels, resulting in a pediatric diabetes diagnosis without the usual hyperglycemic symptoms. Her medical history was notable for premature birth, intrauterine growth restriction, a cardiac murmur from patent ductus arteriosus and a bicuspid aortic valve, delayed teething, and distinct dysmorphic features. Genetic testing identified a novel PIK3R1 gene mutation. Treatment with Metformin significantly improved her glycemic control and lipid profiles. The patient also displayed delayed puberty and polycystic ovary syndrome-like symptoms, but growth hormone deficiency was excluded. Endocrine evaluation for her short stature and lipodystrophy confirmed the presence of the PIK3R1 mutation.

CONCLUSIONS

This case highlights the importance of thorough endocrine and genetic evaluations in patients with complex clinical presentations like SHORT syndrome. The identification of a novel PIK3R1 gene mutation expands the understanding of the genetic basis of this syndrome and underscores the need for individualized treatment approaches.

A multicenter, open-label, single-arm trial of the long-term safety of empagliflozin treatment for refractory diabetes mellitus with insulin resistance (EMPIRE-02)

AIMS/INTRODUCTION

Insulin resistance syndrome and lipoatrophic diabetes are rare conditions characterized by the development of treatment-refractory diabetes with severe insulin resistance. We recently conducted a 24 week, multicenter, single-arm trial (EMPIRE-01) that demonstrated a certain level of effectiveness and safety of empagliflozin for these conditions. To evaluate treatment safety over a longer period, we have now performed an additional 28 week trial (EMPIRE-02) that followed on from EMPIRE-01.

MATERIALS AND METHODS

The primary and secondary outcomes were safety and efficacy evaluations, respectively. All eight subjects of the EMPIRE-01 trial participated in EMPIRE-02.

RESULTS

Twenty adverse events (AEs) were recorded among five individuals during the combined 52 week treatment period of both trials. Whereas one case of chronic hepatitis B was moderate in severity, all other AEs were mild. There were thus no serious AEs or events necessitating discontinuation or suspension of treatment or a reduction in drug dose. Whereas ketoacidosis or marked increases in serum ketone body levels were not observed, the mean body mass of the subjects was decreased slightly after completion of EMPIRE-02. The improvement in mean values of glycemic parameters observed in EMPIRE-01 was not sustained in EMPIRE-02, mostly because of one individual whose parameters deteriorated markedly, likely as a result of nonadherence to diet therapy. The improvement in glycemic parameters was sustained during EMPIRE-02 after exclusion of this subject from analysis.

CONCLUSIONS

Empagliflozin demonstrated a certain level of safety and efficacy for the treatment of insulin resistance syndrome and lipoatrophic diabetes over 52 weeks, confirming its potential as a therapeutic option.

Imprinted Grb10, encoding growth factor receptor bound protein 10, regulates fetal growth independently of the insulin-like growth factor type 1 receptor (Igf1r) and insulin receptor (Insr) genes

BACKGROUND

Optimal size at birth dictates perinatal survival and long-term risk of developing common disorders such as obesity, type 2 diabetes and cardiovascular disease. The imprinted Grb10 gene encodes a signalling adaptor protein capable of inhibiting receptor tyrosine kinases, including the insulin receptor (Insr) and insulin-like growth factor type 1 receptor (Igf1r). Grb10 restricts fetal growth such that Grb10 knockout (KO) mice are at birth some 25-35% larger than wild type. Using a mouse genetic approach, we test the widely held assumption that Grb10 influences growth through interaction with Igf1r, which has a highly conserved growth promoting role.

RESULTS

Should Grb10 interact with Igf1r to regulate growth Grb10:Igf1r double mutant mice should be indistinguishable from Igf1r KO single mutants, which are around half normal size at birth. Instead, Grb10:Igf1r double mutants were intermediate in size between Grb10 KO and Igf1r KO single mutants, indicating additive effects of the two signalling proteins having opposite actions in separate pathways. Some organs examined followed a similar pattern, though Grb10 KO neonates exhibited sparing of the brain and kidneys, whereas the influence of Igf1r extended to all organs. An interaction between Grb10 and Insr was similarly investigated. While there was no general evidence for a major interaction for fetal growth regulation, the liver was an exception. The liver in Grb10 KO mutants was disproportionately overgrown with evidence of excess lipid storage in hepatocytes, whereas Grb10:Insr double mutants were indistinguishable from Insr single mutants or wild types.

CONCLUSIONS

Grb10 acts largely independently of Igf1r or Insr to control fetal growth and has a more variable influence on individual organs. Only the disproportionate overgrowth and excess lipid storage seen in the Grb10 KO neonatal liver can be explained through an interaction between Grb10 and the Insr. Our findings are important for understanding how positive and negative influences on fetal growth dictate size and tissue proportions at birth.

A Multicenter, Open-Label, Single-Arm Trial of the Efficacy and Safety of Empagliflozin Treatment for Refractory Diabetes Mellitus with Insulin Resistance (EMPIRE-01)

INTRODUCTION

Insulin resistance syndrome and lipoatrophic diabetes are characterized by severe insulin resistance and are often refractory to treatment. Trials assessing the efficacy of antidiabetes drugs for these rare conditions have been limited, however. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, which lower glycemia independently of insulin action, have shown efficacy for type 2 diabetes with insulin resistance. We here investigated the efficacy and safety of the SGLT2 inhibitor empagliflozin for treatment of insulin resistance syndrome and lipoatrophic diabetes.

METHODS

The trial was conducted at five academic centers in Japan and included seven patients with insulin resistance syndrome and one patient with lipoatrophic diabetes. Participants received 10 mg of empagliflozin daily. If the hemoglobin A1c (HbA1c) level was ≥ 7.0% (52 mmol/mol) after 12 weeks, the dose was adjusted to 25 mg. The study duration was 24 weeks, and the primary outcome was the change in HbA1c level by the end of the treatment period. Safety evaluations were performed for all participants.

RESULTS

By the end of the 24-week treatment period, the mean HbA1c level for all eight patients had decreased by 0.99 percentage points (10.8 mmol/mol) (95% confidence interval [CI], 0.59 to 1.38 percentage points, 6.6 to 14.9 mmol/mol) and the mean fasting plasma glucose concentration had declined by 63.9 mg/dL (3.55 mmol/L) (95% CI 25.5 to 102.3 mg/dL, 1.42 to 5.68 mmol/L). Continuous glucose monitoring revealed a reduction in mean glucose levels from 164.3 ± 76.1 to 137.6 ± 46.6 mg/dL (9.13 ± 4.23 to 7.65 ± 2.59 mmol/L) as well as an increase in the time in range (70-180 mg/dL) from 58.9 ± 36.1% to 70.8 ± 18.3%. Seventeen mild adverse events were recorded in five individuals throughout the study period. No severe events were reported. The mean body mass showed a slight decrease and the mean serum ketone body concentration showed a slight increase during treatment.

CONCLUSION

Our results demonstrate that empagliflozin shows a certain level of efficacy and safety for treatment of insulin resistance syndrome and lipoatrophic diabetes.

TRIAL REGISTRATION

jRCTs2051190029 and NCT04018365.

A Qualitative Research Study of Experiences and Perceptions of People Living with Insulin Resistance Syndrome or Lipoatrophic Diabetes in Japan

INTRODUCTION

There are few reports on the experiences and perceptions of people living with the rare diseases of insulin resistance syndrome or lipodystrophy. This study was designed to identify treatment experiences and perceptions of disease-related burdens among affected people, as well as their needs and priorities. We discussed how to meet identified needs and expectations, in addition to the types of therapeutic drugs and support required.

METHODS

Qualitative data regarding participants' experiences and perceptions of the diseases were collected through individual interviews, advisory board meetings, and individual follow-up activities. Verbatim transcripts from recorded participants' statements were qualitatively analysed.

RESULTS

Four women aged 30-41 years participated in the study, two with insulin resistance syndrome and two with lipoatrophic diabetes. The diseases not only took a heavy physical toll on these women, but they and their families were also affected psychologically, with some experiencing stigmatisation. There was a lack of information for participants about their disease and little public awareness of the disease. The needs identified include initiatives to promote an accurate understanding of these diseases, information booklets, consultation service for those affected by the diseases, less burdensome treatment options, and opportunities for peer communication.

CONCLUSION

People living with insulin resistance syndrome or lipoatrophic diabetes have significant physical/psychological burdens and unmet needs. The following are highly desirable to alleviate the burdens: promoting proper understanding of the diseases; establishing a framework for dissemination of disease and treatment information to those living with the diseases; development of therapeutic drugs for these diseases; educational materials that raise public awareness; and opportunities for peer communication.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN000043693). A Japanese translation is available for this article.

Endogenous hyperinsulinemic hypoglycemia: case series and literature review

PURPOSE

Endogenous hyperinsulinemic hypoglycemia (EHH) is an uncommon disease characterized by inappropriately high plasma insulin levels despite low plasma glucose levels. Some rare etiologies can lead to EHH. Correct diagnosis is a prerequisite for treatment. Hence, although challenging, it is crucial for patients with EHH to identify the different causes.

METHODS

We describe a case series of three patients, all of whom had obvious hypoglycemic symptoms and extraordinary hyperinsulinemia. Their plasma glucose, insulin, and C-peptide levels were tested simultaneously when hypoglycemia occurred. Moreover, other biochemical indices and relevant antibody levels were measured and imaging examinations were conducted.

RESULTS

According to their medical history, physical examination, laboratory results, and imaging findings, the three patients were diagnosed with insulinoma, type B insulin resistance syndrome, and insulin autoimmune syndrome. After precise treatments, hypoglycemia was ultimately eliminated.

CONCLUSION

Although these diseases have similar symptoms and biochemical abnormalities, the treatment and prognosis are different. The case series presented here highlights the challenges in the differential diagnosis of EHH. An accurate diagnosis is necessary for hypoglycemia treatment.

INSR novel mutations identified in a Chinese family with severe INSR-related insulin resistance syndromes: A case report

RATIONALE

Severe insulin receptor gene (INSR)-related insulin resistance syndromes (SIR) include Donohue syndrome (DS), Rabson-Mendenhall syndrome (RMS), and type A insulin resistance. The incidence of DS is about 1 in 4 million births. We identified novel INSR mutations (c.2246delG and c.2646 + 5G > A) in a patient with SIR, which expanded the variant spectrum and helped to improve the understanding of the diagnosis and treatment of this condition.

PATIENT CONCERNS

A 10-year-old Chinese boy was admitted to the hospital for deepening skin color. He presented with growth retardation, peculiar facial features, acanthosis nigricans, hypertrichosis, extremely high insulin levels, fasting hypoglycemia, and postprandial hyperglycemia, Whole-exome gene testing suggested compound heterozygous mutations in INSR (c.2246delG and c.2646 + 5G > A).

DIAGNOSIS

The diagnosis was SIR. What's more, based on the phenotypic and biographical results, this child did not present typical RMS and DS but rather an intermediate phenotype between the 2 conditions.

INTERVENTIONS

On the basis of a sensible diet and exercise, the patient was prescribed metformin (250 mg) at breakfast and lunch, which was increased to 500 mg after 1 month.

OUTCOMES

After 2 months of treatment, the patient's glycated hemoglobin (HbA1c) levels decreased to 6% but his insulin resistance did not improve significantly.

LESSONS

In children who are not obese but with severe insulin resistance, growth retardation, hirsutism, and hyperglycemia, genetic testing should be performed for early diagnosis, active treatment, and follow-up.

Case report: Successful combination therapy with double-filtration plasmapheresis and rituximab under the condition of the use of a sensor-augmented pump for type B insulin resistance syndrome

Type B insulin resistance syndrome (TBIR) is a rare disease characterized by refractory diabetes due to severe insulin resistance caused by anti-insulin receptor autoantibodies, and a standard treatment regimen for TBIR has not been established, leading to therapeutic difficulties and high mortality. Since TBIR is known to be associated with autoimmune diseases such as systemic lupus erythematosus (SLE), glucocorticoids are often used as key immunosuppressive agents. However, glucocorticoids have the potential to exacerbate the pathophysiology of TBIR by worsening insulin sensitivity, which leads to hyperglycemia and muscle wasting. Here, we report a case history of a 66-year-old man who was diagnosed as having TBIR in combination with SLE and Sjögren's syndrome with marked hyperglycemia, ketosis, and muscle wasting. He was successfully treated with combination therapy of double-filtration plasmapheresis (DFPP) and administration of the anti-CD20 monoclonal antibody rituximab without induction of glucocorticoid therapy while using a sensor-augmented insulin pump (SAP) to prevent hypoglycemia. Remission of diabetes was achieved without severe hypoglycemic events and his circulating insulin receptor antibodies became negative after seven months of initiation of these treatments. Based on the successful clinical courses of this case, our report suggests the possibility of an effective therapeutic regimen with DFPP and rituximab under the condition of the use of an SAP for a patient with TBIR without induction of glucocorticoids.