The ketosis-resistance in fibro-calculous-pancreatic-diabetes. 1. Clinical observations and endocrine-metabolic measurements during oral glucose tolerance test

Comprehensive evaluation of patterns of hypoglycemia unawareness (HUA) and glycemic variability (GV) in patients with fibrocalculous pancreatic diabetes (FCPD): A cross-sectional study from South India

Objectives

Hypoglycemia unawareness (HUA) in patients with FCPD is common with an unclear etiology. We evaluated the prevalence, characteristics of HUA, glycemic variability (GV), its possible association with pancreatic glucagon secretion & cardiac autonomic function in patients with FCPD.

Methods

A two-week ambulatory glucose profile (AGP) and cardiac autonomic function test was done in patients with FCPD (n = 60), and categorized into UNAWARE (n = 44) and AWARE (n = 16) groups based on the Hypoglycemia Unawareness Index (HUI) score. Glycaemic variability was assessed from the AGP data using Easy GV 9.0.2 software. A subset of patients from both the groups (n = 11) underwent a mixed-meal challenge test and were compared with healthy individuals (controls; n = 11).

Results

HUA was evidenced in 73% (44/60) of patients with FCPD. Significant hypoglycemia, nocturnal hypoglycemia, duration of hypoglycemia and poor cardiac autonomic functions (p = 0.01) were prominent in the UNAWARE group. The overall GV was greater in the UNAWARE group. In the UNAWARE group, significantly reduced fasting and post prandial glucagon levels negatively correlated with HUI (r = -0.74, p < 0.05) and GV-hypoglycemia indices (p < 0.05) In contrast, significantly higher post prandial glucagon levels in the AWARE group positively correlated with post prandial hyperglycemia (r = 0.61, p < 0.05).

Conclusion

Heterogeneity in patterns of glucagon secretion were significantly associated with HUA and GV. Reduced glucagon levels contribute to greater risks of HUA, nocturnal hypoglycemia and greater GV, while hyperglucagonemia predisposes to postprandial hyperglycemia and hypoglycemia awareness in patients with FCPD.

REPRINT OF: CLASSIFICATION OF DIABETES MELLITUS

Executive Summary This document updates the 1999 World Health Organization (WHO) classification of diabetes. It prioritizes clinical care and guides health professionals in choosing appropriate treatments at the time of diabetes diagnosis, and provides practical guidance to clinicians in assigning a type of diabetes to individuals at the time of diagnosis. It is a compromise between clinical and aetiological classification because there remain gaps in knowledge of the aetiology and pathophysiology of diabetes. While acknowledging the progress that is being made towards a more precise categorization of diabetes subtypes, the aim of this document is to recommend a classification that is feasible to implement in different settings throughout the world. The revised classification is presented in Table 1. Unlike the previous classification, this classification does not recognize subtypes of type 1 diabetes and type 2 diabetes and includes new types of diabetes ("hybrid types of diabetes" and "unclassified diabetes").

Fibrocalculous pancreatic diabetes

Fibrocalculous pancreatic diabetes (FCPD) is a unique form of diabetes reported from tropical countries, associated with both endocrine and exocrine disease of the pancreas. The pre-diabetic phase of the disease is called tropical chronic pancreatitis (TCP). Currently FCPD is classified as a secondary form of diabetes called pancreatic diabetes, because essentially the disease is caused by pancreatic damage. There is an overlap of these subjects with idiopathic, non-alcoholic pancreatitis. This review will cover the etiopathogenesis, diagnosis and management of this clinical condition. FCPD could lead to endocrine dysfunction (diabetes and its complications) as well as exocrine dysfunction, and is associated with a higher risk of pancreatic cancer, for which early detection is important.

Emerging concepts in the pathogenesis of diabetes in fibrocalculous pancreatic diabetes

Fibrocalcific pancreatic diabetes (FCPD) is a rare form of diabetes affecting people in the tropics and presenting with unique clinical and radiological features. The onset of diabetes usually follows the first few episodes of abdominal pain and develops by the second or third decade of life. Endocrine and exocrine pancreatic insufficiency, brittle glycemic control, and insulin-requiring, ketosis-resistant diabetes are the novel characteristics of FCPD. The etiopathogenetic mechanisms leading to FCPD remain unknown. Although defects in insulin secretion are the major contributors, growing evidence towards a possible role for insulin resistance and body composition abnormalities have added a new dimension to the disease pathogenesis. Deciphering the key pathogenetic mechanisms may have a profound effect on therapeutic strategies in future studies on FCPD.

Fibrocalculous pancreatic diabetes: a case report

BACKGROUND

Diabetes is now becoming a major cause of morbidity and mortality in both developing and developed countries. Even though type 1 and type 2 are the commonest, diabetes mellitus due to secondary causes have been identified. Fibrocalculous Pancreatic Diabetes is a unique entity wherein pancreatic calcification and chronic inflammation lead to exocrine and endocrine failure of the pancreas. This form of non-alcoholic pancreatopathy is exclusively seen among the young, with a male preponderance and commonly in tropical countries where malnutrition and poverty go hand in hand. Whereas, interestingly this case has a late presentation in a female, unlike in other reported cases. For the best of our knowledge this is the first such documented case reported in Sri Lanka.

CASE PRESENTATION

A 57 year old non-alcoholic Sinhalese female from Sri Lanka, presented with a history of chronic pancreatitis of nine years duration, after which she had developed severe Insulin Dependent Diabetes Mellitus. Imaging of the abdomen showed typical pancreatic calcifications, and this presentation accords with the criteria for Fibrocalculous pancreatic diabetes.

CONCLUSION

This case report demonstrates a rare form of secondary diabetes in a middle aged female, without a childhood history of abdominal pain suggestive of pancreatitis, indicating late onset disease. Therefore a high index of suspicion is necessary even though the diagnostic criteria indicates the presence of childhood onset of disease.

TCF7L2 gene polymorphisms do not predict susceptibility to diabetes in tropical calcific pancreatitis but may interact with SPINK1 and CTSB mutations in predicting diabetes

BACKGROUND

Tropical calcific pancreatitis (TCP) is a type of chronic pancreatitis unique to developing countries in tropical regions and one of its important features is invariable progression to diabetes, a condition called fibro-calculous pancreatic diabetes (FCPD), but the nature of diabetes in TCP is controversial. We analysed the recently reported type 2 diabetes (T2D) associated polymorphisms in the TCF7L2 gene using a case-control approach, under the hypothesis that TCF7L2 variants should show similar association if diabetes in FCPD is similar to T2D. We also investigated the interaction between the TCF7L2 variants and N34S SPINK1 and L26V CTSB mutations, since they are strong predictors of risk for TCP.

METHODS

Two polymorphisms rs7903146 and rs12255372 in the TCF7L2 gene were analyzed by direct sequencing in 478 well-characterized TCP patients and 661 healthy controls of Dravidian and Indo-European ethnicities. Their association with TCP with diabetes (FCPD) and without diabetes was tested in both populations independently using chi-square test. Finally, a meta analysis was performed on all the cases and controls for assessing the overall significance irrespective of ethnicity. We dichotomized the whole cohort based on the presence or absence of N34S SPINK1 and L26V CTSB mutations and further subdivided them into TCP and FCPD patients and compared the distribution of TCF7L2 variants between them.

RESULTS

The allelic and genotypic frequencies for both TCF7L2 polymorphisms, did not differ significantly between TCP patients and controls belonging to either of the ethnic groups or taken together. No statistically significant association of the SNPs was observed with TCP or FCPD or between carriers and non-carriers of N34S SPINK1 and L26V CTSB mutations. The minor allele frequency for rs7903146 was different between TCP and FCPD patients carrying the N34S SPINK1 variant but did not reach statistical significance (OR = 1.59, 95% CI = 0.93-2.70, P = 0.09), while, TCF7L2variant showed a statistically significant association between TCP and FCPD patients carrying the 26V allele (OR = 1.69, 95% CI = 1.11-2.56, P = 0.013).

CONCLUSION

Type 2 diabetes associated TCF7L2 variants are not associated with diabetes in TCP. Since, TCF7L2 is a major susceptibility gene for T2D, it may be hypothesized that the diabetes in TCP patients may not be similar to T2D. Our data also suggests that co-existence of TCF7L2 variants and the SPINK1 and CTSB mutations, that predict susceptibility to exocrine damage, may interact to determine the onset of diabetes in TCP patients.

Diabetes mellitus in Tropical Chronic Pancreatitis Is Not Just a Secondary Type of Diabetes

AIMS

In chronic calcific pancreatitis of the tropics, etiology and relationship to developing diabetes mellitus are unknown. Some consider these cases a straightforward secondary type of diabetes, while others suggest selective beta-cell impairment. Testing pancreatic function, we investigated whether selective beta-cell impairment triggers diabetes associated with tropical pancreatitis.

METHODS

At a Bangladeshi research institute, 8 chronic tropical pancreatitis and no diabetes mellitus subjects, 14 fibrocalculous pancreatic diabetics and 27 matched healthy controls underwent arginine (endocrine pancreatic function) and secretin (exocrine pancreatic function assessment) stimulation tests.

RESULTS

All patients with clinically-diagnosed, chronic pancreatitis demonstrated pronounced exocrine pancreatic dysfunction with beta-cell functioning differing significantly between the two groups. Compared to controls, patients having tropical pancreatitis and no diabetes showed normal plasma C-peptide values at baseline and after arginine stimulation, while fibrocalculous pancreatic diabetics demonstrated a typical diabetic pattern for plasma C-peptide levels. In contrast, pancreatic alpha-cell functioning (glucagon response to arginine) was preserved in both pancreatitis groups.

CONCLUSION

A preserved pancreatic alpha-cell function in diabetics with advanced chronic pancreatitis of the tropics supports the concept of two different pathogenic mechanisms, one eliciting chronic pancreatitis and the other selective pancreatic beta-cell impairment and subsequent diabetes mellitus.

Tropical chronic pancreatitis

Tropical chronic pancreatitis (TCP) is a juvenile form of chronic calcific non-alcoholic pancreatitis, seen almost exclusively in the developing countries of the tropical world. The classical triad of TCP consists of abdominal pain, steatorrhoea, and diabetes. When diabetes is present, the condition is called fibrocalculous pancreatic diabetes (FCPD) which is thus a later stage of TCP. Some of the distinctive features of TCP are younger age at onset, presence of large intraductal calculi, more aggressive course of the disease, and a high susceptibility to pancreatic cancer. Pancreatic calculi are the hallmark for the diagnosis of TCP and in non-calcific cases ductal dilation on endoscopic retrograde cholangiopancreatography, computed tomography, or ultrasound helps to identify the disease. Diabetes is usually quite severe and of the insulin requiring type, but ketosis is rare. Microvascular complications of diabetes occur as frequently as in type 2 diabetes but macrovascular complications are uncommon. Pancreatic enzyme supplements are used for relief of abdominal pain and reducing the symptoms related to steatorrhoea. Early diagnosis and better control of the endocrine and exocrine dysfunction could help to ensure better survival and improve the prognosis and quality of life of TCP patients.

Tropical chronic pancreatitis: an update

Tropical chronic pancreatitis represents a juvenile nonalcoholic form of chronic pancreatitis prevalent in many tropical developing countries. Tropical chronic pancreatitis differs from temperate zone pancreatitis in its younger age of onset, more accelerated course, higher prevalence of pancreatic calculi and diabetes, and greater propensity to pancreatic malignancy. The diabetic stage of the disease is referred to as fibrocalculous pancreatic diabetes. The diabetes is severe and insulin requiring although ketosis resistant. Diabetic complications occur in fibrocalculous pancreatic diabetes just like in other primary forms of diabetes. The etiology of tropical chronic pancreatitis remains unclear, although malnutrition along with dietary cyanogen toxicity, antioxidant deficiency, and a genetic predisposition have been proposed. In the last few decades, the prognosis has markedly improved as a result of better management of diabetes. Yet a better understanding of the pathogenesis of tropical chronic pancreatitis could further improve treatment options and offer an opportunity for prevention of this disorder, which leads to severe morbidity in a large proportion of affected patients.

Histopathology and immunohistochemistry of pancreatic islets in fibrocalculous pancreatic diabetes

The histopathology of Fibrocalculous Pancreatic Diabetes (FCPD) has been extensively studied, but there are no reports on alteration in patterns of hormone secreting cells using immunohistochemistry in islets of FCPD patients. In this study, we report on the histopathology and immunohistochemistry of islets of FCPD patients and its possible correlation with the clinical picture. Pancreatic biopsies were carried out in six patients with FCPD at the time of surgery for abdominal pain. Routine histopathology and immunohistochemistry studies were carried out with six primary antibodies namely insulin, glucagon, pancreatic polypeptide (PP), somatostatin, vasoactive intestinal peptide and gastrin. Histopathology of the pancreas showed a spectrum of changes ranging from moderate to severe atrophy, fibrosis of the parenchyma and degeneration of the ducts. Nesidioblastosis was present in three patients. Immunohistochemical studies showed a decrease in the number of islets but some patients showed evidence of hyperplasia. There was an overall decrease in the percent of insulin cells and the positivity in the islets correlated with plasma C-peptide levels and the duration of diabetes. There was no consistent relationship with glucagon with some patients showing increased and other decreased positivity. There was a marked decrease in PP and somatostatin positivity, the significance of which is not clear. The reduction, but partial preservation of insulin positivity is consistent with the ketosis resistance shown by patients with Fibrocalculous Pancreatic Diabetes.

Ketosis resistance in fibrocalculous pancreatic diabetes: II. Hepatic ketogenesis after oral medium-chain triglycerides

A majority of patients with fibrocalculous pancreatic diabetes (FCPD) do not become ketotic even in adverse conditions. It is not clear whether this ketosis resistance is due to reduced fatty acid release from adipose tissue or to impaired hepatic ketogenesis. We tested hepatic ketogenesis in FCPD patients using a ketogenic challenge of oral medium-chain triglycerides (MCTs) and compared it with that in matched insulin-dependent diabetes mellitus (IDDM) patients and healthy controls. After oral MCTs, FCPD patients showed only a mild increase in blood 3-hydroxybutyrate (3-HB) concentrations (median: fasting, 0.13 mmol/L; peak, 0.52) compared with IDDM patients (fasting, 0.44; peak, 3.39) and controls (fasting, 0.04; peak, 0.75). Plasma nonesterified fatty acid (NEFA) concentrations were comparable in the two diabetic groups (FCPD: fasting, 0.50 mmol/L; peak, 0.79; IDDM: fasting, 0.91; peak, 1.04). Plasma C-peptide concentrations were low and comparable in the two diabetic groups. Plasma glucagon concentrations were higher in IDDM patients in the fasting state, but declined to levels comparable to those in FCPD patients after oral MCTs. Plasma carnitine concentrations were comparable in the two groups of patients. It is concluded that the failure to stimulate ketogenesis under these conditions could be partly due to inhibition of a step beyond fatty acid entry into the mitochondria.