# Secondary Diabetes > Secondary diabetes causes — pancreatic, endocrinopathies, drugs, fibrocalculous pancreatic diabetes — explained for NEET-PG Medicine exams. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/secondary-diabetes-causes - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Secondary Diabetes", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/secondary-diabetes-causes ## Direct answer Think of secondary diabetes in three buckets: pancreatic disease (pancreatitis, pancreatectomy, trauma, cystic fibrosis, haemochromatosis — and in India the classic fibrocalculous pancreatic diabetes), endocrinopathies that raise counter-regulatory hormones (acromegaly, Cushing's syndrome, phaeochromocytoma, glucagonoma, somatostatinoma, hyperthyroidism, aldosteronism via hypokalaemia), and drugs (glucocorticoids, thiazides, atypical antipsychotics, tacrolimus, protease inhibitors, statins at the margin). The clinical prize is double: an unsuspected cause found behind "poorly controlled type 2 diabetes", and the knowledge that treating the cause — transsphenoidal surgery for acromegaly, adrenaline blockade and resection for phaeochromocytoma — often improves or cures the hyperglycaemia. ## What you must remember - Endocrine causes by hormone: growth hormone and cortisol (insulin resistance), catecholamines (both resistance and reduced secretion), glucagon, and somatostatin (suppressed insulin and glucagon). - Pancreatic (type 3c) diabetes: chronic pancreatitis is the leading cause; features include exocrine insufficiency, fat malabsorption, and brittle control from lost glucagon — hypoglycaemia risk is high. - Fibrocalculous pancreatic diabetes: young, thin patients from tropical regions including southern India, with abdominal pain, pancreatic duct calculi on a plain abdominal X-ray, and insulin requirement with low ketoacidosis risk. - Haemochromatosis: "bronze diabetes" — iron deposition in the pancreas with cirrhosis, skin pigmentation, arthropathy and cardiomyopathy; transferrin saturation is the screen. - Drug list to memorise: glucocorticoids, thiazides, atypical antipsychotics (olanzapine, clozapine), tacrolimus and ciclosporin, HIV protease inhibitors, niacin; beta-blockers and insulin secretagogues mainly mask rather than cause. - Mitochondrial diabetes (A3243G mutation): maternally inherited diabetes with sensorineural deafness (MELAS-family syndromes). - Steroid-induced hyperglycaemia follows the steroid's time-action — prednisolone raises afternoon glucose most; once-daily morning dosing confines the damage. ## How to work through the diagnosis A 46-year-old "type 2" farmer from Kerala, BMI 19, has needed insulin since diagnosis at 30, gets frequent hypoglycaemia, and reports bulky, floating stools. The pattern is wrong for type 2: thin, insulin-dependent yet hypo-prone, with steatorrhoea. A plain X-ray of the abdomen shows pancreatic calculi — the near-pathognomonic image of fibrocalculous pancreatic diabetes, a form of type 3c disease described classically in tropical south Asia. Management pivots: pancreatic enzyme replacement, low-fat diet, insulin with hypoglycaemia vigilance (glucagon reserve is gone), fat-soluble vitamin supplementation, and an abdominal CT to define duct anatomy, since endoscopic or surgical drainage of a dilated duct can ease pain. Now a different vignette: a 38-year-old with "difficult diabetes" and blood pressures of 160/100 despite three agents, recent-onset headache, palpitations and pallor episodes. Before escalating insulin, screen for phaeochromocytoma with plasma or urinary metanephrines — the catecholamine excess both causes hyperglycaemia and makes intervening blindly dangerous. Similarly, a young patient with coarse facial features, new shoe-ring tightness and snoring needs IGF-1 testing for acromegaly; diabetes in acromegaly is driven by growth hormone and improves substantially after tumour control. In each case the diabetes is the smoke, not the fire. Steroid diabetes deserves its own algorithm: glucose rising only after prednisolone starts, peaking in the afternoon. Prefer once-daily morning steroids, add therapy timed to cover that window (or adjust basal insulin upward), and reassess whether the steroid can be tapered — the hyperglycaemia of short courses usually resolves within days of stopping. ## Where students slip The exam-ready trap is the well-controlled list recited without mechanism — examiners follow with "why does aldosteronism cause diabetes?" (hypokalaemia impairs beta-cell insulin secretion), and "why is hypoglycaemia common in pancreatic diabetes?" (loss of glucagon). The second slip is calling every thin young diabetic "type 1" in a tropical setting: fibrocalculous pancreatic diabetes is a standard Indian differential, and the plain X-ray finding of duct calculi is a one-line answer candidates should own. Third, thiazides and steroids are repeatedly forgotten as iatrogenic causes in "worsening diabetes" stems — scan the drug list before scanning the pancreas. Finally, acanthosis nigricans points to insulin resistance and type 2, not to endocrine tumours; using it wrongly in a thin patient wastes the clue. ## Frequently asked questions ### Which endocrinopathies most commonly cause secondary diabetes? Acromegaly, Cushing's syndrome and phaeochromocytoma lead the list, with glucagonoma and somatostatinoma as rarer causes; hyperaldosteronism contributes through hypokalaemia-induced insulin secretory failure. ### What is fibrocalculous pancreatic diabetes? A form of secondary (type 3c) diabetes seen in tropical regions including India: young, lean patients with chronic pancreatitis, pancreatic duct calculi visible on plain X-ray or CT, exocrine insufficiency, and insulin-requiring but ketosis-resistant diabetes. ### Why is hypoglycaemia common in pancreatic diabetes? Both insulin and glucagon-secreting islets are destroyed, so counter-regulation is blunted; insulin therapy becomes brittle, with abrupt swings and poor recovery from lows. ### Do drugs cause true diabetes or just worsen glucose? Glucocorticoids, thiazides, atypical antipsychotics, calcineurin inhibitors and protease inhibitors can induce persistent hyperglycaemia and true diabetes in predisposed people; the changes are often dose-related and partly reversible on withdrawal. ### How does haemochromatosis present as diabetes? Iron deposition damages pancreatic islets, producing diabetes alongside cirrhosis, bronze skin pigmentation, arthropathy of the second and third metacarpophalangeal joints, and sometimes cardiomyopathy — transferrin saturation above about 45% is the screening test.