Unexpected case of postnatal pancreatitis: first presentation of autoimmune diabetes

Background

Gestational diabetes mellitus (GDM) is defined as the first presentation of glucose intolerance in pregnancy without prior known diabetes. In Singapore, universal screening between 26 and 28 weeks in pregnancy is adopted and the incidence of GDM locally is 18.9%.1 While GDM increases the risk of progression to type 2 diabetes in later life, 10% of these women may have autoantibodies against pancreatic β-cells, which increases their risk of progression to type 1 diabetes or otherwise known as latent autoimmune diabetes of adulthood (LADA).2 We present a case of a young healthy woman with GDM in pregnancy who developed acute pancreatic ketoacidosis postnatally. She was subsequently found to have islet-cells autoantibody and has been insulin-dependent since then. Written patient consent was obtained for this case report.

Case presentation

A primigravida Southeast Asian patient in her 30s booked early with a spontaneous singleton pregnancy. Her body mass index (BMI) was 19.2 kg/m². Routine antenatal investigations were normal. Subsequent fetal anomaly scan was normal.

GDM was diagnosed at 25 weeks using the international association of the diabetes and pregnancy study groups (IADPSG)criteria.3 Three-point oral glucose tolerance test showed fasting glucose reading of 4.1 mmol/L, 1-hour glucose reading of 10.1 mmol/L and 2-hour glucose reading of 8.0 mmol/L. She was initially able to maintain good blood sugar readings with professional dietary advice. Fetal growth scans were normal at 18, 32 and 36 weeks. Oral metformin 250 mg two times per day was started at 36 weeks as her capillary blood glucose (CBG) readings were suboptimal. She was non-compliant to metformin due to side effects of nausea and vomiting despite the low dosage. She delivered a healthy baby boy of birth weight 2934 g via an emergency caesarean section for labour dystocia. Surgery was uneventful and she had an unremarkable recovery.

On the third postoperative day, she developed acute abdominal and chest pain with generalised weakness. Mild fever of 37.5°C and mild tachycardia of 108 beats per minute were noted, while remaining normotensive. She saturated well at oxygen saturation (SpO2) of 98% on room air. She was alert but distressed. Tenderness over her right hypochondrium was elicited but there were no signs of acute abdomen. Caesarean scar wound was intact. A stat CBG was unrecordable. ECG showed normal sinus rhythm.

Investigations

Interim investigations revealed a raised total white cell count of 37×10⁹ /L, C reactive protein 86 mg/L, serum lactate of 2.5 mmol/L and serum procalcitonin of 2.62 µg/L. Electrolyte derangements include hyponatraemia (sodium 126 mmol/L) and hyperkalaemia (potassium 6.6 mmol/L). Her liver function test, amylase and lipase levels were normal. CT of abdomen and pelvis showed a normal gallbladder, biliary tree and pancreas with no surgical complications. Nonetheless empirical broad-spectrum intravenous antibiotics of ceftriaxone and metronidazole were started.

Despite supportive management, the patient did not improve and became progressively more delirious. She was transferred to the intensive care unit (ICU). Renal panel results now returned with a high serum glucose of 33 mmol/L; an intravenous Insulin bolus of 10 units was administered immediately. Serum ketones were also raised at 2.4 mmol/L. Clinical impression was that of diabetic ketoacidosis (DKA). A multidisciplinary team involving high-risk obstetricians, obstetric anaesthetist, as well as endocrinologist, were gathered.

Her serum glucose, serum ketones and lactate showed improvement after commencement of insulin infusion and treatment (table 1). Tachycardia remained persistent at 130 bpm despite 3.5 L of fluid challenge. Repeat ECG showed atrial flutter, which was attributed to refractory metabolic acidosis despite aggressive intravenous sodium bicarbonate treatment. Her management was escalated to a medical ICU for continuous renal replacement therapy (CRRT).

Amylase and lipase were subsequently both found to be elevated at 1187 U/L and>600 U/L, respectively, 15 hours after the onset of her symptoms. A diagnosis of Acute Pancreatitis with Glasglow Score 3 (neutrophil count of 18.9×10⁹ /L, serum glucose of 18.2 mmol/L and serum albumin of 27 g/L) was made. Lipid panel and toxicology screen were normal.

Further autoimmune investigations were commenced with the consideration of autoimmune pancreatitis as a potential cause. Results returned positive test for anti-glutamic acid decarboxylase antibody (anti-GAD), which suggested a new manifestation of insulin-dependent DM from pancreatic islet cell destruction. The rest of the autoimmune panel (ANA, Anti-DS DNA, ENA screen, anti-neutrophil cytoplasmic antibody, anti-islet cell antibody, rheumatoid factor, CCP antibody) were negative.

Treatment

Patient clinically improved after 3 hours of CRRT and intravenous insulin was converted to subcutaneous (SC) insulin the next day. Her atrial flutter also resolved with the resolution of metabolic acidosis, with a formal two-dimensional transthoracic echocardiogram showing normal left ventricular size and normal ejection fraction of 57%. Thromboprophylaxis was commenced and she was discharged home on SC insulin on postoperative day 8.

Outcome and follow-up

An interval 6 weeks’ postnatal MR cholangiopancreatography done was normal. A 2-month follow-up by the endocrinologist suggested long-term insulin requirement due to her autoimmune diabetes. She was advised to continue SC Lantus 12 units OM and SC Novorapid four units three times a day. She remained well at her 1-year follow-up.