Diagnosis and treatment of anti-insulin antibody-mediated labile glycaemia in insulin-treated diabetes.

AIMS: Anti-insulin antibodies in insulin-treated diabetes can derange glycaemia, but are under-recognised. Detection of significant antibodies is complicated by antigenically distinct insulin analogues. We evaluated a pragmatic biochemical approach to identifying actionable antibodies, and assessed its utility in therapeutic decision making. METHODS: Forty people with insulin-treated diabetes and combinations of insulin resistance, nocturnal/matutinal hypoglycaemia, and unexplained ketoacidosis were studied using broad-specificity insulin immunoassays, polyethylene glycol (PEG) precipitation and gel filtration chromatography (GFC) with or without ex vivo insulin preincubation. RESULTS: Twenty-seven people had insulin immunoreactivity (IIR) below 3000 pmol/L that fell less than 50% after PEG precipitation. Insulin binding by antibodies in this group was low and judged insignificant. In 8 people IIR was above 3000 pmol/L and fell by more than 50% after PEG precipitation. GFC demonstrated substantial high molecular weight (HMW) IIR in 7 of these 8. In this group antibodies were judged likely significant. In 2 people immunosuppression was introduced, with a good clinical result in one but only a biochemical response in another. In 6 people adjustment of insulin delivery was subsequently informed by knowledge of underlying antibody. In a final group of 5 participants IIR was below 3000 pmol/L but fell by more than 50% after PEG precipitation. In 4 of these GFC demonstrated low levels of HMW IIR and antibody significance was judged indeterminate. CONCLUSIONS: Anti-insulin antibodies should be considered in insulin-treated diabetes with unexplained glycaemic lability. Combining immunoassays with PEG precipitation can stratify their significance. Antibody depletion may be beneficial, but conservative measures often suffice.

Proceedings of the annual meeting of the European Consortium of Lipodystrophies (ECLip) Cambridge, UK, 7-8 April 2022.

Lipodystrophy syndromes are rare diseases with defects in the development or maintenance of adipose tissue, frequently leading to severe metabolic complications. They may be genetic or acquired, with variable clinical forms, and are largely underdiagnosed. The European Consortium of Lipodystrophies, ECLip, is a fully functional non-profit network of European centers of excellence working in the field of lipodystrophies. It provides a favorable environment to promote large Europe-wide and international collaborations to increase the basic scientific understanding and clinical management of these diseases. It works with patient advocacy groups to increase public awareness. The network also promotes a European Patient Registry of lipodystrophies, as a collaborative research platform for consortium members. The annual congress organized gives an update of the findings of network research groups, highlighting clinical and fundamental aspects. The talks presented during the meeting in Cambridge, UK, in 2022 are summarized in these minutes.

Describing the natural history of clinical, biochemical and radiological outcomes of children with familial partial lipodystrophy type 2 (FPLD2) from the United Kingdom: A retrospective case series.

CONTEXT: Familial partial lipodystrophy type 2 (FPLD2) results from autosomal dominant mutations in the LMNA gene, causing lack of subcutaneous fat deposition and excess ectopic fat accumulation, leading to metabolic complications and reduced life expectancy. The rarity of the condition means that the natural history of FPLD2 throughout childhood is not well understood. We report outcomes in a cohort of 12 (5M) children with a genetic diagnosis of FPLD2, under the care of the UK National Severe Insulin Resistance Service (NSIRS) which offers multidisciplinary input including dietetic, in addition to screening for comorbidities. OBJECTIVE: To describe the natural history of clinical, biochemical and radiological outcomes of children with FPLD2. DESIGN: A retrospective case note review of children with a genetic diagnosis of FPLD2 who had been seen in the paediatric NSIRS was performed. PATIENTS: Twelve (5M) individuals diagnosed with FPLD2 via genetic testing before age 18 and who attended the NSIRS clinic were included. MEASUREMENTS: Relationships between metabolic variables (HbA1c, triglycerides, fasting insulin, fasting glucose and alanine transaminase [ALT]) across time, from first visit to most recent, were explored using a multivariate model, adjusted for age and gender. The age of development of comorbidities was recorded. RESULTS: Three patients (all female) developed diabetes between 12 and 19 years and were treated with Metformin. One female has hypertrophic cardiomyopathy and four (1M) patients developed mild hepatic steatosis at a median [range] age of 14(12-15) years. Three (1M) patients reported mental health problems related to lipodystrophy. There was no relationship between biochemical results and age. Patients with diabetes had higher concentrations of ALT than patients who did not have diabetes, adjusted for age, gender and body mass index standard deviation scores. CONCLUSIONS: Despite dietetic input, some patients, more commonly females, developed comorbidities after the age of 10. The absence of relationships between biochemical results and age likely reflects a small cohort size. We propose that, while clinical review and dietetic support are beneficial for children with FPLD2, formal screening for comorbidities before age 10 may not be of benefit. Clinical input from an multidisciplinary team including dietician, psychologist and clinician should be offered after diagnosis.

Bilateral macular drusen in acquired partial lipodystrophy with type 2 membranoproliferative glomerulonephritis.

A 35-year-old woman with acquired partial lipodystrophy (PLD) and features of type 2 membranoproliferative glomerulonephritis (MPGN-II), presented with difficulty in her fine detailed vision over the past year. She had right amblyopia from a hypermetropic anisometropia with astigmatism, displaying a best-corrected visual acuity of 0.50 and 0.00 LogMAR, in the right and left eye, respectively. Funduscopy showed bilateral symmetrical drusenoid deposits most prominent in the temporal macula with clusters in the superior and inferior retina, outside the temporal vascular arcades. Multimodal retinal imaging was performed, which confirmed hyperautofluorescent drusen located between the retinal pigment epithelium and Bruch's membrane. Electroretinography showed bilateral mild peripheral macular dysfunction, but normal central macular function on the pattern electroretinogram. Both PLD and macular drusen, are rare as distinct disease entities, but an association does exist and may be linked to MPGN-II.

Ovarian Hyperandrogenism and Response to Gonadotropin-releasing Hormone Analogues in Primary Severe Insulin Resistance.

CONTEXT: Insulin resistance (IR) is associated with polycystic ovaries and hyperandrogenism, but underpinning mechanisms are poorly understood and therapeutic options are limited. OBJECTIVE: To characterize hyperandrogenemia and ovarian pathology in primary severe IR (SIR), using IR of defined molecular etiology to interrogate disease mechanism. To extend evaluation of gonadotropin-releasing hormone (GnRH) analogue therapy in SIR. METHODS: Retrospective case note review in 2 SIR national referral centers. Female patients with SIR with documented serum total testosterone (TT) concentration. RESULTS: Among 185 patients with lipodystrophy, 65 with primary insulin signaling disorders, and 29 with idiopathic SIR, serum TT ranged from undetectable to 1562 ng/dL (54.2 nmol/L; median 40.3 ng/dL [1.40 nmol/L]; n = 279) and free testosterone (FT) from undetectable to 18.0 ng/dL (0.625 nmol/L; median 0.705 ng/dL [0.0244 nmol/L]; n = 233). Higher TT but not FT in the insulin signaling subgroup was attributable to higher serum sex hormone-binding globulin (SHBG) concentration. Insulin correlated positively with SHBG in the insulin signaling subgroup, but negatively in lipodystrophy. In 8/9 patients with available ovarian tissue, histology was consistent with polycystic ovary syndrome (PCOS). In 6/6 patients treated with GnRH analogue therapy, gonadotropin suppression improved hyperandrogenic symptoms and reduced serum TT irrespective of SIR etiology. CONCLUSION: SIR causes severe hyperandrogenemia and PCOS-like ovarian changes whether due to proximal insulin signaling or adipose development defects. A distinct relationship between IR and FT between the groups is mediated by SHBG. GnRH analogues are beneficial in a range of SIR subphenotypes.

Recent developments in lipodystrophy.

PURPOSE OF REVIEW: Lipodystrophy syndromes have an estimated prevalence of 1.3-4.7 cases per million and as with other rare diseases conducting research can be challenging. The present review highlights recently published work that has provided insights into the field of non-HIV--associated lipodystrophy syndromes. RECENT FINDINGS: Lipodystrophies are a heterogenous group of disorders, as such research is often focused on specific subtypes of the condition. The identification of children carrying LMNA mutations has provided insights into the natural history of FPLD2, specifically that the adipose tissue phenotype predates the onset of puberty. Recent reports of PLIN1 heterozygous null variant carriers and the apparent absence of a lipodystrophy phenotype challenges our understanding of the molecular biology of perilipin 1 and its role in the pathogenesis of FPLD4. With a focus on therapeutics, studies delineating the differential responsiveness of PPARγ mutants to endogenous and synthetic ligands has illustrated the potential for pharmacogenetics to inform therapeutic decisions in lipodystrophy related to PPARG mutations, whereas robust human studies have provided insight into the food independent metabolic effects of leptin in lipodystrophy. Finally, rare syndromes of lipodystrophy continue to serve as an exemplar for the contribution of genetically determined adipose tissue expandability to metabolic disease in the general population. SUMMARY: Lipodystrophy research continues to illuminate our understanding of this rare disease and the possibility that lipodystrophy syndromes and the metabolic syndrome may have shared pathophysiology.

"We're stuck with what we've got": The impact of lipodystrophy on body image.

AIMS AND OBJECTIVES: To evaluate the impact of lipodystrophy on body image and how this affects patients' daily lives. BACKGROUND: Lipodystrophy refers to a group of rare conditions characterised by generalised or partial lack of body fat and is associated with severe metabolic problems, for example, severe insulin resistance, diabetes and pancreatitis. In addition to its metabolic effect, lack of adipose tissue may have a major impact on appearance and cause distressing physical changes. While global research has focused on diagnosis and management, there is no published work investigating the psychological effects of lipodystrophy on body image. METHODS: Following ethical approval, participants with lipodystrophy were purposively sampled from the National Severe Insulin Resistance Service in Cambridge, UK, and invited to take part in a semi-structured interview. Eleven (10 female, one male) interviews were conducted and digitally recorded. Data were analysed using an inductive thematic approach. RESULTS: Four main themes were identified in the data set; "Always feeling appearance was different," "a better understanding of lipodystrophy is needed," "feeling accepted" and "there's more to lipodystrophy than managing symptoms." Participants spoke of distressing cosmetic effects related to lack of fat tissue and other changes related to lipodystrophy, contributing to negative body image. For some, negative body image led to feelings of worthlessness impacting daily life and adherence to treatment. Psychological support was lacking but desired by participants. CONCLUSION: Lipodystrophy contributes to negative body image affecting patients' daily lives. Patients wanted psychological support alongside medical management. Further research is needed to determine how best to deliver psychological support and to evaluate its impact on well-being and metabolic management. RELEVANCE TO CLINICAL PRACTICE: The effects of rare diseases such as lipodystrophy on appearance can be distressing for patients. Support beyond medical management is needed to improve patients' daily lives and help them to live well with appearance-altering conditions.

The metabolic syndrome- associated small G protein ARL15 plays a role in adipocyte differentiation and adiponectin secretion.

Common genetic variants at the ARL15 locus are associated with plasma adiponectin, insulin and HDL cholesterol concentrations, obesity, and coronary atherosclerosis. The ARL15 gene encodes a small GTP-binding protein whose function is currently unknown. In this study adipocyte-autonomous roles for ARL15 were investigated using conditional knockdown of Arl15 in murine 3T3-L1 (pre)adipocytes. Arl15 knockdown in differentiated adipocytes impaired adiponectin secretion but not adipsin secretion or insulin action, while in preadipocytes it impaired adipogenesis. In differentiated adipocytes GFP-tagged ARL15 localized predominantly to the Golgi with lower levels detected at the plasma membrane and intracellular vesicles, suggesting involvement in intracellular trafficking. Sequencing of ARL15 in 375 severely insulin resistant patients identified four rare heterozygous variants, including an early nonsense mutation in a proband with femorogluteal lipodystrophy and non classical congenital adrenal hyperplasia, and an essential splice site mutation in a proband with partial lipodystrophy and a history of childhood yolk sac tumour. No nonsense or essential splice site mutations were found in 2,479 controls, while five such variants were found in the ExAC database. These findings provide evidence that ARL15 plays a role in adipocyte differentiation and adiponectin secretion, and raise the possibility that human ARL15 haploinsufficiency predisposes to lipodystrophy.

Roux-en-Y Gastric Bypass Surgery in the Management of Familial Partial Lipodystrophy Type 1.

Context: Familial partial lipodystrophy type 1 (FPLD1) is an extreme form of central adiposity, with peripheral lipodystrophy associated with severe manifestations of the metabolic syndrome, often poorly responsive to standard therapeutic approaches. Body mass index in FPLD1 varies but, in many cases, is below the level at which metabolic surgery is usually considered as a therapeutic option. Design: We detailed the metabolic response to gastric bypass surgery of three patients with FPLD1, refractory to medical therapy. Results: Roux-en-Y gastric bypass (RYGB) was associated with weight loss and substantial improvements in glycemic control and insulin sensitivity. All three patients were able to stop using insulin. Glucose tolerance testing in one patient demonstrated an increase in L-cell-derived gut hormone responses postoperatively. Conclusion: RYGB surgery substantially improved glycemic control in three patients with FPLD1, two of whom had body mass indices below 30 kg/m2. RYGB should be considered in patients with partial lipodystrophy and refractory metabolic disease.

Diagnosis of insulin autoimmune syndrome using polyethylene glycol precipitation and gel filtration chromatography with ex vivo insulin exchange.

CONTEXT: Insulin-binding antibodies may produce severe dysglycaemia in insulin-naïve patients ('insulin autoimmune syndrome' (IAS) or Hirata disease), while rendering routine insulin assays unreliable. OBJECTIVE: To assess the performance of clinically used insulin assays and an optimal analytical approach in the context of IAS. DESIGN: Observational biochemical study of selected patients with hyperinsulinaemic hypoglycaemia. PATIENTS: Three patients without diabetes with recurrent spontaneous hyperinsulinaemic hypoglycaemia and 'positive' insulin antibodies. MEASUREMENTS: A panel of clinically used insulin assays (Siemens ADVIA® Centaur, Siemens Immulite® 2000, DiaSorin LIAISON® XL, PE AutoDELFIA® and the Beckman Coulter Access® 2) were used before and after plasma dilution or polyethylene glycol (PEG) precipitation. Anti-insulin IgG antibodies were measured by Isletest™ -IAA ELISA. Gel filtration chromatography (GFC) was undertaken with and without preincubation of plasma with exogenous insulin. RESULTS: Dilution of IAS plasma with assay-specific buffer increased insulin recovery, supporting negative immunoassay interference by antibodies. PEG precipitation of IAS plasma decreased insulin recovery using all assays except the Immulite® 2000. GFC discriminated high molecular weight and monomeric insulin, while ex vivo addition of exogenous insulin to plasma increased insulin bound to antibody, thereby improving the sensitivity of detection of insulin immunocomplexes. CONCLUSIONS: Immunoprecipitation with PEG must be used with caution in screening for insulin-antibody complexes as results are assay dependent. GFC with addition of exogenous insulin can identify significant insulin immunocomplexes with enhanced sensitivity, with attendant greater clinical utility and avoidance of radiolabelled reagents.

Metabolic insights from extreme human insulin resistance phenotypes.

As well as improving diagnostic and clinical outcomes for affected patients, understanding the genetic basis of rare human metabolic disorders has resulted in several fundamental biological insights. In some cases understanding extreme phenotypes has also informed thinking about more prevalent metabolic diseases. Insulin resistance underpins the twin epidemics of obesity and type 2 diabetes as well as accounting for many of the metabolic problems encompassed by the term metabolic syndrome. This review provides a brief update on current understanding of human severe insulin resistance syndromes, before highlighting recent insights provided by studies in these rare syndromes into the molecular pathogenesis of elements of the metabolic syndrome.

A double-blind, placebo-controlled, crossover trial comparing the effects of amiloride and hydrochlorothiazide on glucose tolerance in patients with essential hypertension.

Hypertension guidelines advise limiting the dose of thiazide diuretics and avoiding combination with ß-blockade, because of increased risk of diabetes mellitus. We tested whether changes in the 2-hour oral glucose tolerance test could be detected after 4 weeks of treatment with a thiazide and could be avoided by switching to amiloride. Two double-blind, placebo-controlled, crossover studies were performed. In study 1 (41 patients), we found that changes in glucose during a 2-hour oral glucose tolerance test could be detected after 4 weeks of treatment with bendroflumethiazide. In study 2, 37 patients with essential hypertension received, in random order, 4 weeks of once-daily treatment with hydrochlorothiazide (HCTZ) 25 to 50 mg, nebivolol 5 to 10 mg, combination (HCTZ 25-50 mg+nebivolol 5-10 mg), amiloride (10-20 mg), and placebo. Each drug was force titrated at 2 weeks and separated by a 4-week placebo washout. At each visit, we recorded blood pressure and performed a 75-g oral glucose tolerance test. Primary outcome was the difference in glucose (over the 2 hours of the oral glucose tolerance test) between 0 and 4 weeks, when HCTZ and amiloride were compared by repeated-measures analysis. For similar blood pressure reductions, there were opposite changes in glucose between the 2 diuretics (P<0.0001). Nebivolol did not impair glucose tolerance, either alone or in combination. There was a negative correlation between Δpotassium and Δ2-hour glucose (r=-0.28; P<0.0001). In 2 crossover studies, 4 weeks of treatment with a thiazide diuretic impaired glucose tolerance. No impairment was seen with K(+)-sparing diuretic or ß(1)-selective blockade. Substitution or addition of amiloride may be the solution to preventing thiazide-induced diabetes mellitus.

Mitochondrial oxidative phosphorylation is impaired in patients with congenital lipodystrophy.

OBJECTIVE: Lipid accumulation in skeletal muscle and the liver is strongly implicated in the development of insulin resistance and type 2 diabetes, but the mechanisms underpinning fat accrual in these sites remain incompletely understood. Accumulating evidence of muscle mitochondrial dysfunction in insulin-resistant states has fuelled the notion that primary defects in mitochondrial fat oxidation may be a contributory mechanism. The purpose of our study was to determine whether patients with congenital lipodystrophy, a disorder primarily affecting white adipose tissue, manifest impaired mitochondrial oxidative phosphorylation in skeletal muscle. RESEARCH DESIGN AND METHODS: Mitochondrial oxidative phosphorylation was assessed in quadriceps muscle using 31P-magnetic resonance spectroscopy measurements of phosphocreatine recovery kinetics after a standardized exercise bout in nondiabetic patients with congenital lipodystrophy and in age-, gender-, body mass index-, and fitness-matched controls. RESULTS: The phosphocreatine recovery rate constant (k) was significantly lower in patients with congenital lipodystrophy than in healthy controls (P<0.001). This substantial (∼35%) defect in mitochondrial oxidative phosphorylation was not associated with significant changes in basal or sleeping metabolic rates. CONCLUSIONS: Muscle mitochondrial oxidative phosphorylation is impaired in patients with congenital lipodystrophy, a paradigmatic example of primary adipose tissue dysfunction. This finding suggests that changes in mitochondrial oxidative phosphorylation in skeletal muscle could, at least in some circumstances, be a secondary consequence of adipose tissue failure. These data corroborate accumulating evidence that mitochondrial dysfunction can be a consequence of insulin-resistant states rather than a primary defect. Nevertheless, impaired mitochondrial fat oxidation is likely to accelerate ectopic fat accumulation and worsen insulin resistance.

Percentage of body fat and plasma glucose predict plasma sialic acid concentration in type 2 diabetes mellitus.

Circulating sialic acid is an independent risk factor for cardiovascular disease and is higher in people with type 2 diabetes mellitus. Sialic acid is associated with body mass index, but it is uncertain whether body fat contributes to the higher levels of sialic acid in type 2 diabetes mellitus. Therefore, we have investigated whether the higher levels of sialic acid observed in type 2 diabetes mellitus persist when controlling for fatness. Fasting plasma samples were collected from 24 individuals with type 2 diabetes mellitus and 24 controls. Percentage of body fat was measured by bioelectrical impedance. Plasma sialic acid was quantified by an enzymatic method. Plasma sialic acid was higher in the group with type 2 diabetes mellitus than controls (602 +/- 14 vs 545 +/- 14 mg/L, P = .007). Percentage of body fat was associated with plasma sialic acid concentration in both the control group (r = 0.481, P = .020) and the group with type 2 diabetes mellitus (r = 0.527, P = .007). Fasting glucose was also associated with plasma sialic acid in the group with type 2 diabetes mellitus (r = 0.700, P < .001). Adjustment for percentage of body fat accounted for the higher levels of sialic acid in type 2 diabetes mellitus. Using linear regression, 54.3% of the variation of plasma sialic acid was explained by percentage of body fat and glucose concentrations in the whole group. Seventy-four percent of sialic acid variation was explained by the same model in type 2 diabetes mellitus. In conclusion, this is the first study to show that percentage of body fat predicts plasma sialic acid concentration and contributes toward higher levels of sialic acid in type 2 diabetes mellitus.

Premenopausal advantages in postprandial lipid metabolism are lost in women with type 2 diabetes.

OBJECTIVE: Women with type 2 diabetes appear to lose the protection against cardiovascular disease afforded by estrogens. We examined the effects of menopausal status on postprandial clearance of dietary fat in healthy and diabetic women. RESEARCH DESIGN AND METHODS: Fasting subjects (premenopausal and postmenopausal control subjects, premenopausal and postmenopausal diabetic women, all n = 8) were given a meal containing the stable isotope 1,1,1-(13)C-tripalmitin, with blood and breath sampled for 6 and 24 h, respectively, in the postprandial period. Lower levels of (13)C-palmitic acid ((13)C-PA) in the triglyceride fraction implies more efficient chylomicron clearance, lower levels of (13)C-PA in the nonesterified fatty acid (NEFA) fraction implies improved dietary NEFA entrapment, and higher levels of (13)CO(2) in the breath denote more efficient of oxidation of dietary-derived lipid. RESULTS: In diabetic women, there were no differences between the pre- and postmenopausal groups for any of these parameters. In contrast, premenopausal control subjects, compared with postmenopausal control subjects, had lower (13)C-PA in the triglyceride fraction area under the curve (AUC) (premenopausal median [range] 25.2 [12.1-49.4 mmol/l] per 6 h, postmenopausal 48.5 [15.5-77.2 mmol/l] per 6 h; P < 0.01) and higher (13)CO(2) levels in the breath AUC (premenopausal 22.5 [18.0-31.5%] of administered dose, postmenopausal 17.2 [11.2-31.5%] of administered dose; P < 0.01) with no difference between groups in levels of (13)C-PA in the NEFA fraction AUC. CONCLUSIONS: The premenopausal advantage in clearance of dietary lipid is not seen in premenopausal diabetic women. This is likely to promote an atherogenic lipoprotein profile and may contribute to the loss of cardiovascular disease protection seen in diabetic women.