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Open access

N Siddique, R Durcan, S Smyth, T Kyaw Tun, S Sreenan and J H McDermott

Summary

We present three cases of acute diabetic neuropathy and highlight a potentially underappreciated link between tightening of glycaemic control and acute neuropathies in patients with diabetes. Case 1: A 56-year-old male with poorly controlled type 2 diabetes (T2DM) was commenced on basal-bolus insulin. He presented 6 weeks later with a diffuse painful sensory neuropathy and postural hypotension. He was diagnosed with treatment-induced neuropathy (TIN, insulin neuritis) and obtained symptomatic relief from pregabalin. Case 2: A 67-year-old male with T2DM and chronic hyperglycaemia presented with left lower limb pain, weakness and weight loss shortly after achieving target glycaemia with oral anti-hyperglycaemics. Neurological examination and neuro-electrophysiological studies suggested diabetic lumbosacral radiculo-plexus neuropathy (DLPRN, diabetic amyotrophy). Pain and weakness resolved over time. Case 3: A 58-year-old male was admitted with blurred vision diplopia and complete ptosis of the right eye, with intact pupillary reflexes, shortly after intensification of glucose-lowering treatment with an SGLT2 inhibitor as adjunct to metformin. He was diagnosed with a pupil-sparing third nerve palsy secondary to diabetic mononeuritis which improved over time. While all three acute neuropathies have been previously well described, all are rare and require a high index of clinical suspicion as they are essentially a diagnosis of exclusion. Interestingly, all three of our cases are linked by the development of acute neuropathy following a significant improvement in glycaemic control. This phenomenon is well described in TIN, but not previously highlighted in other acute neuropathies.

Learning points:

  • A link between acute tightening of glycaemic control and acute neuropathies has not been well described in literature.
  • Clinicians caring for patients with diabetes who develop otherwise unexplained neurologic symptoms following a tightening of glycaemic control should consider the possibility of an acute diabetic neuropathy.
  • Early recognition of these neuropathies can obviate the need for detailed and expensive investigations and allow for early institution of appropriate pain-relieving medications.
Open access

Janani Devaraja, Charlotte Elder and Adrian Scott

Summary

This case report describes a family pedigree of a mother and her children with an E227K mutation in the KCNJ11 gene. People with this particular gene mutation typically present with transient neonatal diabetes; with more than half the cohort relapsing into permanent diabetes in adolescence or early adulthood. However, the mother developed diabetes as an adolescent and thus was initially diagnosed as having Type 1 Diabetes. All her children have inherited the same genetic mutation but with differing presentations. Her second, third and fourth child presented with transient neonatal diabetes which remitted at varying times. Her first child is 16 years old but had not developed diabetes at the time of writing. The KCNJ11 gene codes for the KIR6.2 subunit of the KATP channels of the pancreatic beta cells. Mutations in this gene limit insulin release from beta cells despite high blood glucose concentrations. Most people with diabetes caused by this genetic mutation can be successfully managed with glibenclamide. Learning of the genetic mutation changed the therapeutic approach to the mother’s diabetes and enabled rapid diagnosis for her children. Through this family, we identified that an identical genetic mutation does not necessarily lead to the same diabetic phenotype. We recommend clinicians to consider screening for this gene in their patients whom MODY is suspected; especially in those presenting before the age of 25 who remain C-peptide positive.

Learning points:

  • KATP channel closure in pancreatic beta cells is a critical step in stimulating insulin release. Mutations in the KIR6.2 subunit can result in the KATP channels remaining open, limiting insulin release.
  • People with KCNJ11 mutations may not present with neonatal diabetes as the age of presentation of diabetes can be highly variable.
  • Most affected individuals can be treated successfully with glibenclamide, which closes the KATP channels via an independent mechanism.
  • All first degree relatives of the index case should be offered genetic testing, including asymptomatic individuals. Offspring of affected individuals should be monitored for neonatal diabetes from birth.
  • Affected individuals will require long-term follow-up as there is a high risk of recurrence in later life.
Open access

Khaled Aljenaee, Osamah Hakami, Colin Davenport, Gemma Farrell, Tommy Kyaw Tun, Agnieszka Pazderska, Niamh Phelan, Marie-Louise Healy, Seamus Sreenan and John H McDermott

Summary

Measurement of glycated haemoglobin (HbA1c) has been utilised in assessing long-term control of blood glucose in patients with diabetes, as well as diagnosing diabetes and identifying patients at increased risk of developing diabetes in the future. HbA1c reflects the level of blood glucose to which the erythrocyte has been exposed during its lifespan, and there are a number of clinical situations affecting the erythrocyte life span in which HbA1c values may be spuriously high or low and therefore not reflective of the true level of glucose control. In the present case series, we describe the particulars of three patients with diabetes who had spuriously low HbA1c levels as a result of dapsone usage. Furthermore, we discuss the limitations of HbA1c testing and the mechanisms by which it may be affected by dapsone in particular.

Learning points:

  • Various conditions and medications can result in falsely low HbA1c.
  • Dapsone can lead to falsely low HbA1c by inducing haemolysis and by forming methaemoglobin.
  • Capillary glucose measurement, urine glucose measurements and fructosamine levels should be used as alternatives to HbA1c for monitoring glycaemic control if it was falsely low or high.
Open access

Michal Barabas, Isabel Huang-Doran, Debbie Pitfield, Hazel Philips, Manoj Goonewardene, Ruth T Casey and Benjamin G Challis

Summary

A 67-year-old woman presented with a generalised rash associated with weight loss and resting tachycardia. She had a recent diagnosis of diabetes mellitus. Biochemical evaluation revealed elevated levels of circulating glucagon and chromogranin B. Cross-sectional imaging demonstrated a pancreatic lesion and liver metastases, which were octreotide-avid. Biopsy of the liver lesion confirmed a diagnosis of well-differentiated grade 2 pancreatic neuroendocrine tumour, consistent with metastatic glucagonoma. Serial echocardiography commenced 4 years before this diagnosis demonstrated a progressive left ventricular dilatation and dysfunction in the absence of ischaemia, suggestive of glucagonoma-associated dilated cardiomyopathy. Given the severity of the cardiac impairment, surgical management was considered inappropriate and somatostatin analogue therapy was initiated, affecting clinical and biochemical improvement. Serial cross-sectional imaging demonstrated stable disease 2 years after diagnosis. Left ventricular dysfunction persisted, however, despite somatostatin analogue therapy and optimal medical management of cardiac failure. In contrast to previous reports, the case we describe demonstrates that chronic hyperglucagonaemia may lead to irreversible left ventricular compromise. Management of glucagonoma therefore requires careful and serial evaluation of cardiac status.

Learning points:

  • In rare cases, glucagonoma may present with cardiac failure as the dominant feature. Significant cardiac impairment may occur in the absence of other features of glucagonoma syndrome due to subclinical chronic hyperglucagonaemia.
  • A diagnosis of glucagonoma should be considered in patients with non-ischaemic cardiomyopathy, particularly those with other features of glucagonoma syndrome.
  • Cardiac impairment due to glucagonoma may not respond to somatostatin analogue therapy, even in the context of biochemical improvement.
  • All patients with a new diagnosis of glucagonoma should be assessed clinically for evidence of cardiac failure and, if present, a baseline transthoracic echocardiogram should be performed. In the presence of cardiac impairment these patients should be managed by an experienced cardiologist.
Open access

Aoife Garrahy, Matilde Bettina Mijares Zamuner and Maria M Byrne

Summary

Coexistence of autoimmune diabetes and maturity-onset diabetes of the young (MODY) is rare. We report the first case of coexisting latent autoimmune diabetes of adulthood (LADA) and glucokinase (GCK) MODY. A 32-year-old woman was treated with insulin for gestational diabetes at age 32 years; post-partum, her fasting blood glucose was 6.0 mmol/L and 2-h glucose was 11.8 mmol/L following an oral glucose tolerance test, and she was maintained on diet alone. Five years later, a diagnosis of LADA was made when she presented with fasting blood glucose of 20.3 mmol/L and HbA1C 125 mmol/mol (13.6%). GCK-MODY was identified 14 years later when genetic testing was prompted by identification of a mutation in her cousin. Despite multiple daily insulin injections her glycaemic control remained above target and her clinical course has been complicated by multiple episodes of hypoglycaemia with unawareness. Although rare, coexistence of latent autoimmune diabetes of adulthood and monogenic diabetes should be considered if there is a strong clinical suspicion, for example, family history. Hypoglycaemic unawareness developed secondary to frequent episodes of hypoglycaemia using standard glycaemic targets for LADA. This case highlights the importance of setting fasting glucose targets within the expected range for GCK-MODY in subjects with coexisting LADA.

Learning points:

  • We report the first case of coexisting latent autoimmune diabetes of adulthood (LADA) and GCK-MODY.
  • It has been suggested that mutations in GCK may lead to altered counter-regulation and recognition of hypoglycaemia at higher blood glucose levels than patients without such mutation. However, in our case, hypoglycaemic unawareness developed secondary to frequent episodes of hypoglycaemia using standard glycaemic targets for LADA.
  • This case highlights the importance of setting fasting glucose targets within the expected range for GCK-MODY in subjects with coexisting LADA to avoid hypoglycaemia.
Open access

Akihiko Ando, Shoichiro Nagasaka and Shun Ishibashi

Summary

We report a case of a woman with diabetes mellitus caused by a genetic defect in ABCC8-coding sulfonylurea receptor 1 (SUR1), a subunit of the ATP-sensitive potassium (KATP) channel protein. She was diagnosed with diabetes at 7 days after birth. After intravenous insulin drip for 1 month, her hyperglycaemia remitted. At the age of 13 years, her diabetes relapsed, and after that she had been treated by intensive insulin therapy for 25 years with relatively poor glycaemic control. She was switched to oral sulfonylurea therapy and attained euglycaemia. In addition, her insulin secretory capacity was ameliorated gradually.

Learning points:

  • Genetic testing should be considered in any individuals or family with diabetes that occurred within the first year or so of life.
  • Sulfonylurea can achieve good glycaemic control in patients with KATP channel mutations by restoring endogenous insulin secretion, even if they were treated with insulin for decades.
  • Early screening and genetic testing are important to improve the prognosis of patients with neonatal diabetes mellitus arising from ABCC8 or KCNJ11 mutation.
Open access

Tess Jacob, Renee Garrick and Michael D Goldberg

Summary

Metformin is recommended as the first-line agent for the treatment of type 2 diabetes. Although this drug has a generally good safety profile, rare but potentially serious adverse effects may occur. Metformin-associated lactic acidosis, although very uncommon, carries a significant risk of mortality. The relationship between metformin accumulation and lactic acidosis is complex and is affected by the presence of comorbid conditions such as renal and hepatic disease. Plasma metformin levels do not reliably correlate with the severity of lactic acidosis. We present a case of inadvertent metformin overdose in a patient with both renal failure and hepatic cirrhosis, leading to two episodes of lactic acidosis and hypoglycemia. The patient was successfully treated with hemodialysis both times and did not develop any further lactic acidosis or hypoglycemia, after the identification of metformin tablets accidentally mixed in with his supply of sevelamer tablets. Early initiation of renal replacement therapy is key in decreasing lactic acidosis-associated mortality.

Learning points:

  • When a toxic ingestion is suspected, direct visualization of the patient’s pills is advised in order to rule out the possibility of patient- or pharmacist-related medication errors.
  • Though sending a specimen for determination of the plasma metformin concentration is important when a metformin-treated patient with diabetes presents with lactic acidosis, complex relationships exist between metformin accumulation, hyperlactatemia and acidosis, and the drug may not always be the precipitating factor.
  • Intermittent hemodialysis is recommended as the first-line treatment for metformin-associated lactic acidosis (MALA).
  • An investigational delayed-release form of metformin with reduced systemic absorption may carry a lower risk for MALA in patients with renal insufficiency, in whom metformin therapy may presently be contraindicated.
Open access

Elena Carrillo, Amparo Lomas, Pedro J Pinés and Cristina Lamas

Summary

Mutations in hepatocyte nuclear factor 1β gene (HNF1B) are responsible for a multisystemic syndrome where monogenic diabetes (classically known as MODY 5) and renal anomalies, mostly cysts, are the most characteristic findings. Urogenital malformations, altered liver function tests, hypomagnesemia or hyperuricemia and gout are also part of the syndrome. Diabetes in these patients usually requires early insulinization. We present the case of a young non-obese male patient with a personal history of renal multicystic dysplasia and a debut of diabetes during adolescence with simple hyperglycemia, negative pancreatic autoimmunity and detectable C-peptide levels. He also presented epididymal and seminal vesicle cysts, hypertransaminasemia, hyperuricemia and low magnesium levels. In the light of these facts we considered the possibility of a HNF1B mutation. The sequencing study of this gene confirmed a heterozygous mutation leading to a truncated and less functional protein. Genetic studies of his relatives were negative; consequently, it was classified as a de novo mutation. In particular, our patient maintained good control of his diabetes on oral antidiabetic agents for a long period of time. He eventually needed insulinization although oral therapy was continued alongside, allowing reduction of prandial insulin requirements. The real prevalence of mutations in HNF1B is probably underestimated owing to a wide phenotypical variability. As endocrinologists, we should consider this possibility in young non-obese diabetic patients with a history of chronic non-diabetic nephropathy, especially in the presence of some of the other characteristic manifestations.

Learning points:

  • HNF1B mutations are a rare cause of monogenic diabetes, often being a part of a multisystemic syndrome.
  • The combination of young-onset diabetes and genitourinary anomalies with slowly progressive nephropathy of non-diabetic origin in non-obese subjects should rise the suspicion of such occurrence. A family history may not be present.
  • Once diagnosis is made, treatment of diabetes with oral agents is worth trying, since the response can be sustained for a longer period than the one usually described. Oral treatment can help postpone insulinization and, once this is necessary, can help reduce the required doses.
Open access

Murray B Gordon and Kellie L Spiller

Summary

Long-acting pasireotide is an effective treatment option for acromegaly, but it is associated with hyperglycemia, which could impact its use in patients with diabetes. We present a case of a 53-year-old man with acromegaly and type 2 diabetes mellitus (glycated hemoglobin (HbA1c): 7.5%), who refused surgery to remove a pituitary macroadenoma and enrolled in a Phase 3 clinical trial comparing long-acting pasireotide and long-acting octreotide in acromegalic patients. The patient initially received octreotide, but insulin-like growth factor 1 (IGF-1) levels remained elevated after 12 months (383.9 ng/mL; 193.0 ng/mL; reference range: 86.5–223.8 ng/mL), indicating uncontrolled acromegaly. He switched to pasireotide 40 mg and subsequently increased to 60 mg. Within 6 months, IGF-1 levels normalized (193.0 ng/mL), and they were mostly normal for the next 62 months of treatment with pasireotide (median IGF-1: 190.7 ng/mL). Additionally, HbA1c levels remained similar to or lower than baseline levels (range, 6.7% to 7.8%) during treatment with pasireotide despite major changes to the patient’s antidiabetic regimen, which included insulin and metformin. Uncontrolled acromegaly can result in hyperglycemia due to an increase in insulin resistance. Despite having insulin-requiring type 2 diabetes, the patient presented here did not experience a long-term increase in HbA1c levels upon initiating pasireotide, likely because long-term control of acromegaly resulted in increased insulin sensitivity. This case highlights the utility of long-acting pasireotide to treat acromegaly in patients whose levels were uncontrolled after long-acting octreotide and who manage diabetes with insulin.

Learning points

  • Long-acting pasireotide provided adequate, long-term biochemical control of acromegaly in a patient with insulin-requiring type 2 diabetes mellitus who was unresponsive to long-acting octreotide.
  • Glycemic levels initially increased after starting treatment with pasireotide but quickly stabilized as acromegaly became controlled.
  • Long-acting pasireotide, along with an appropriate antidiabetic regimen, may be a suitable therapy for patients with acromegaly who also have insulin-requiring type 2 diabetes mellitus.
Open access

E Rapti, S Karras, M Grammatiki, A Mousiolis, X Tsekmekidou, E Potolidis, P Zebekakis, M Daniilidis and K Kotsa

Summary

Latent autoimmune diabetes in adults (LADA) is a relatively new type of diabetes with a clinical phenotype of type 2 diabetes (T2D) and an immunological milieu characterized by high titers of islet autoantibodies, resembling the immunological profile of type 1 diabetes (T1D). Herein, we report a case of a young male, diagnosed with LADA based on both clinical presentation and positive anti-glutamic acid decarboxylase antibodies (GAD-abs), which were normalized after combined treatment with a dipeptidyl peptidase-4 inhibitor (DPP-4) (sitagliptin) and cholecalciferol.

Learning points

  • Anti-glutamic acid decarboxylase antibodies (GAD-abs) titers in young patients being previously diagnosed as type 2 diabetes (T2D) may help establish the diagnosis of latent autoimmune diabetes in adults (LADA).
  • Sitagliptin administration in patients with LADA might prolong the insulin-free period.
  • Vitamin D administration in patients with LADA might have a protective effect on the progression of the disease.