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Diabetes and brief review for neet pg preparation

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"Diabetes Mellitus"[MeSH Terms]

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American Diabetes Association Standards of Care 2026 diagnosis classification diabetes

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Diabetes Mellitus: NEET PG Rapid Review

Definition

Diabetes mellitus is chronic hyperglycemia due to defective insulin secretion, insulin action, or both.

Classification

  1. Type 1 DM
    • Autoimmune destruction of pancreatic beta cells
    • Absolute insulin deficiency
    • Common in children/young adults, but can occur at any age
    • Associated antibodies: anti-GAD65 most common, IA-2, insulin autoantibody, ZnT8
    • Prone to diabetic ketoacidosis (DKA)
  2. Type 2 DM
    • Insulin resistance + progressive beta-cell dysfunction
    • Most common type
    • Associated with obesity, family history, sedentary lifestyle
    • Usually no ketosis, but can develop HHS
  3. Gestational DM
    • Diabetes first diagnosed in the second or third trimester, not overt diabetes before pregnancy.
  4. Other specific types
    • MODY
    • Pancreatic disease: chronic pancreatitis, pancreatic surgery, hemochromatosis
    • Endocrinopathies: Cushing syndrome, acromegaly, pheochromocytoma
    • Drugs: glucocorticoids, thiazides, atypical antipsychotics, protease inhibitors
    • Genetic insulin receptor defects

Diagnosis of Diabetes

Any one of these establishes diabetes. In an asymptomatic person, confirm with repeat testing on another day.
TestDiabetesPrediabetes
Fasting plasma glucose≥126 mg/dL100-125 mg/dL
2-hour plasma glucose after 75 g OGTT≥200 mg/dL140-199 mg/dL
HbA1c≥6.5%5.7-6.4%
Random plasma glucose with classic symptoms/hyperglycemic crisis≥200 mg/dL-
Fasting means at least 8 hours with no caloric intake.

High-yield caveats for HbA1c

HbA1c may be unreliable in:
  • Hemolytic anemia, blood loss, transfusion
  • Hemoglobinopathies
  • Pregnancy
  • CKD, especially dialysis
  • Conditions with altered RBC lifespan
The current ADA diagnostic standards retain these core diagnostic thresholds.

Type 1 vs Type 2 DM

FeatureType 1 DMType 2 DM
Main defectAbsolute insulin deficiencyInsulin resistance with relative deficiency
Body habitusUsually leanOften overweight/obese
OnsetAbruptGradual
AutoantibodiesPresentAbsent
C-peptideLow/absentNormal or high initially
DKACommonUncommon
TreatmentInsulin mandatoryLifestyle + drugs, insulin if needed
C-peptide reflects endogenous insulin secretion because it is released with endogenous insulin but is absent in administered insulin preparations.

Pathogenesis Pearls

Type 1 DM

  • T-cell mediated autoimmune beta-cell destruction.
  • HLA association: HLA-DR3 and DR4, also DQ2/DQ8.
  • May coexist with autoimmune thyroid disease, celiac disease, Addison disease, pernicious anemia.

Type 2 DM: “Ominous octet”

  1. Decreased insulin secretion from beta cells
  2. Increased hepatic glucose output
  3. Muscle insulin resistance
  4. Increased lipolysis in adipose tissue
  5. Reduced incretin effect
  6. Increased glucagon secretion
  7. Increased renal glucose reabsorption
  8. Central neurotransmitter dysfunction

Symptoms

  • Polyuria, polydipsia, polyphagia
  • Weight loss, fatigue
  • Blurring of vision
  • Recurrent infections: candidiasis, skin/UTI
  • Poor wound healing
  • Neuropathy symptoms

Acute Complications

1. Diabetic Ketoacidosis: DKA

Typical setting: Type 1 DM, infection, missed insulin, MI, stroke.
Triad
  • Hyperglycemia: usually >250 mg/dL
  • Ketosis: serum beta-hydroxybutyrate or urine ketones
  • High-anion-gap metabolic acidosis: pH <7.30, bicarbonate <18 mEq/L
Key mechanism: insulin deficiency causes lipolysis, ketogenesis, dehydration and metabolic acidosis.
Management sequence
  1. IV isotonic fluid
  2. Check and correct potassium
  3. IV insulin infusion
  4. Add dextrose once glucose falls to about 200 mg/dL, while continuing insulin until ketosis resolves
  5. Treat precipitating cause
Potassium rule
  • K+ <3.3 mEq/L: give potassium first, withhold insulin
  • K+ 3.3-5.2: start potassium with fluids
  • K+ >5.2: no initial replacement but monitor closely

2. Hyperosmolar Hyperglycemic State: HHS

  • Usually Type 2 DM, elderly
  • Severe hyperglycemia, often >600 mg/dL
  • High effective serum osmolality, severe dehydration
  • Minimal/absent ketosis and acidosis
  • More profound neurologic manifestations than DKA
DKA vs HHS: DKA = ketosis/acidosis; HHS = extreme dehydration/hyperosmolality.

3. Hypoglycemia

Usually blood glucose <70 mg/dL.
Adrenergic symptoms: sweating, tremor, palpitations, anxiety, hunger.
Neuroglycopenic symptoms: confusion, abnormal behavior, seizure, coma.
Treatment:
  • Conscious: oral glucose
  • Unconscious: IV dextrose or IM/SC glucagon

Chronic Complications

Microvascular

  1. Retinopathy
    • Nonproliferative: microaneurysms, dot-blot hemorrhages, hard exudates
    • Proliferative: neovascularization
    • Macular edema is a major cause of visual loss.
  2. Nephropathy
    • Earliest clinical marker: moderately increased albuminuria, urine albumin-creatinine ratio 30-300 mg/g.
    • Earliest structural lesion: GBM thickening
    • Classic lesion: Kimmelstiel-Wilson nodular glomerulosclerosis
    • ACE inhibitor or ARB is used for albuminuric diabetic kidney disease, especially with hypertension.
  3. Neuropathy
    • Distal symmetric sensorimotor polyneuropathy: stocking-glove pattern
    • Autonomic neuropathy: gastroparesis, erectile dysfunction, orthostatic hypotension, bladder dysfunction.

Macrovascular

  • Coronary artery disease
  • Stroke
  • Peripheral arterial disease

Other high-yield associations

  • Diabetic foot: neuropathy + ischemia + infection
  • Charcot joint
  • Recurrent infections
  • Acanthosis nigricans: insulin resistance
  • Diabetic dermopathy: shin spots

Treatment of Type 2 DM: Exam Framework

Lifestyle

  • Diet, weight loss, regular exercise
  • Stop smoking
  • Manage hypertension and dyslipidemia

Drug classes

ClassMain actionImportant adverse effect / pearl
MetforminDecreases hepatic gluconeogenesisGI upset, B12 deficiency, lactic acidosis risk in severe renal dysfunction
SulfonylureasIncrease insulin releaseHypoglycemia, weight gain
MeglitinidesShort-acting insulin secretagoguesHypoglycemia; taken before meals
GLP-1 receptor agonistsIncrease insulin, reduce glucagon, delay gastric emptyingWeight loss, GI effects; avoid in medullary thyroid carcinoma/MEN2
DPP-4 inhibitorsIncrease endogenous incretin actionWeight neutral; pancreatitis is a known concern
SGLT2 inhibitorsIncrease urinary glucose lossGenital infections, volume depletion, euglycemic DKA
ThiazolidinedionesImprove insulin sensitivity via PPAR-gammaEdema, weight gain, fractures; avoid in heart failure
InsulinReplaces/supplements insulinHypoglycemia, weight gain

Very frequently asked drug facts

  • Metformin: first-line drug in many patients with Type 2 DM.
  • SGLT2 inhibitors: benefit in heart failure and chronic kidney disease, but can cause euglycemic DKA.
  • GLP-1 receptor agonists: promote significant weight loss and have cardiovascular benefit in appropriate patients.
  • Pioglitazone: can worsen heart failure.
  • Sulfonylureas: cause hypoglycemia and weight gain.
  • Insulin is mandatory in Type 1 DM.

Insulin Preparations

TypeExamples
Rapid actingLispro, Aspart, Glulisine
Short actingRegular insulin
Intermediate actingNPH
Long actingGlargine, Detemir, Degludec
Regular insulin
  • Given IV in DKA.
  • Only insulin routinely used IV.
NPH insulin
  • Intermediate acting, has a peak.
  • Can cause nocturnal hypoglycemia.
Glargine
  • Long acting, relatively peakless.
  • Should not be mixed with other insulins.

NEET PG One-Liners

  • Most common type of diabetes: Type 2 DM
  • Most common cause of death in diabetes: cardiovascular disease
  • Most common cause of ESRD in many populations: diabetic kidney disease
  • Earliest clinical sign of diabetic nephropathy: moderately increased albuminuria
  • Earliest retinal lesion: microaneurysm
  • Most common diabetic neuropathy: distal symmetric polyneuropathy
  • Specific antibody for Type 1 DM: anti-GAD
  • Best marker of endogenous insulin secretion: C-peptide
  • Classical lesion in diabetic nephropathy: Kimmelstiel-Wilson nodules
  • DKA acid-base disorder: high-anion-gap metabolic acidosis
  • HHS has: marked hyperosmolarity with minimal ketosis
  • Drug causing euglycemic DKA: SGLT2 inhibitor
  • Drug associated with lactic acidosis: metformin
  • Drug class associated with edema and heart failure exacerbation: thiazolidinediones
  • Common adult monogenic diabetes: MODY
  • Commonest MODY subtype: HNF1A-MODY
  • MODY often responds well to: sulfonylureas, especially HNF1A/HNF4A forms

Memory Aid

“Diabetes complications: RNN + CVS”
  • Retinopathy
  • Nephropathy
  • Neuropathy
  • Coronary artery disease
  • Vascular peripheral disease
  • Stroke

Make a one-page diabetes rapid revision PDF

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ADA Standards of Care 2026 diagnostic criteria diabetes fasting plasma glucose HbA1c

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mkdir -p "/tmp/workspace/diabetes-rapid-revision/src" "/tmp/workspace/diabetes-rapid-revision/output" && python - <<'PY' from reportlab.lib.pagesizes import A4 from reportlab.pdfgen import canvas from reportlab.lib import colors from reportlab.lib.units import mm from reportlab.pdfbase.pdfmetrics import stringWidth from reportlab.pdfbase.ttfonts import TTFont from reportlab.pdfbase import pdfmetrics from reportlab.pdfbase.pdfmetrics import registerFontFamily from reportlab.lib.colors import HexColor from reportlab.pdfbase.ttfonts import TTFont import os out='/tmp/workspace/diabetes-rapid-revision/output/Diabetes_NEETPG_Rapid_Revision.pdf' W,H=A4 c=canvas.Canvas(out,pagesize=A4) c.setTitle('Diabetes Mellitus - NEET PG Rapid Revision') c.setAuthor('Orris') # Palette NAVY=HexColor('#123047'); BLUE=HexColor('#186A8C'); TEAL=HexColor('#138D75'); RED=HexColor('#B03A2E'); GOLD=HexColor('#B9770E'); PALE=HexColor('#F3F7F9'); LIGHTBLUE=HexColor('#EAF4F8'); LIGHTRED=HexColor('#FDEDEC'); GRAY=HexColor('#4D5656'); WHITE=colors.white # helpers def rect(x,y,w,h,fill,stroke=None, radius=0): c.setFillColor(fill) c.setStrokeColor(stroke or fill) c.roundRect(x,y,w,h,radius,fill=1,stroke=1 if stroke else 0) def text(x,y,s,font='Helvetica',size=7.2,color=GRAY): c.setFillColor(color); c.setFont(font,size); c.drawString(x,y,s) def linewrap(s, font, size, maxw): words=s.split(); lines=[]; line='' for word in words: t=(line+' '+word).strip() if stringWidth(t,font,size)<=maxw: line=t else: lines.append(line); line=word if line: lines.append(line) return lines def para(x,y,s,width,size=6.5,leading=7.8,font='Helvetica',color=GRAY,bullet=None): c.setFont(font,size); c.setFillColor(color) indent=7 if bullet else 0 for i,ln in enumerate(linewrap(s,font,size,width-indent)): if i==0 and bullet: c.drawString(x,y,bullet) c.drawString(x+indent,y,ln) y-=leading return y def section(x,top,w,title,color=BLUE): rect(x,top-13,w,13,color) text(x+5,top-9,title,'Helvetica-Bold',7.6,WHITE) return top-18 def keyrow(x,y,label,value,w, labelcolor=NAVY): c.setFont('Helvetica-Bold',6.15); c.setFillColor(labelcolor); c.drawString(x,y,label) lw=stringWidth(label,'Helvetica-Bold',6.15) c.setFont('Helvetica',6.15); c.setFillColor(GRAY); c.drawString(x+lw+2,y,value) return y-8.4 # background c.setFillColor(HexColor('#FFFFFF')); c.rect(0,0,W,H,fill=1,stroke=0) # Header rect(0,H-55,W,55,NAVY) text(19,H-24,'DIABETES MELLITUS','Helvetica-Bold',18,WHITE) text(19,H-38,'NEET PG • ONE-PAGE RAPID REVISION','Helvetica-Bold',7.5,HexColor('#B9E5F4')) # badge rect(W-91,H-43,70,23,TEAL,radius=11) text(W-80,H-34,'EXAM HIGH-YIELD','Helvetica-Bold',6.7,WHITE) margin=16; gap=7; colw=(W-2*margin-gap)/2 L=margin; R=margin+colw+gap; top=H-65 # LEFT COLUMN # Diagnosis Y=section(L,top,colw,'1. DIAGNOSIS: KNOW THE CUT-OFFS') rect(L,Y-45,colw,43,LIGHTBLUE) text(L+5,Y-10,'DIABETES (any one)', 'Helvetica-Bold',6.6,NAVY) rows=[('FPG','≥126 mg/dL'),('2-h 75 g OGTT','≥200 mg/dL'),('HbA1c','≥6.5%'),('Random + classic symptoms/crisis','≥200 mg/dL')] y=Y-18 for a,b in rows: c.setFont('Helvetica-Bold',6.15);c.setFillColor(NAVY);c.drawString(L+5,y,a) c.setFont('Helvetica-Bold',6.15);c.setFillColor(RED);c.drawRightString(L+colw-5,y,b);y-=7.3 Y-=51 text(L,Y,'Prediabetes: FPG 100-125 | 2-h OGTT 140-199 | HbA1c 5.7-6.4%', 'Helvetica-Bold',6.05,GOLD) Y-=10 Y=para(L,Y,'Asymptomatic patient: confirm on a separate day. HbA1c may be unreliable with altered RBC survival, hemoglobinopathies, pregnancy, transfusion, or advanced CKD.',colw,6.05,7.2) Y-=4 # Classification Y=section(L,Y,colw,'2. CLASSIFICATION + DIFFERENTIATION') # mini table rect(L,Y-40,colw,38,PALE) text(L+5,Y-10,'FEATURE','Helvetica-Bold',6,NAVY); text(L+67,Y-10,'TYPE 1','Helvetica-Bold',6,NAVY);text(L+111,Y-10,'TYPE 2','Helvetica-Bold',6,NAVY) data=[('Defect','Absolute insulin ↓','Insulin resistance'),('C-peptide','Low/absent','N/high initially'),('Antibodies','GAD, IA-2, ZnT8','Absent'),('DKA','Common','Uncommon')] y=Y-17 for a,b,d in data: text(L+5,y,a,'Helvetica',5.65,GRAY);text(L+67,y,b,'Helvetica',5.65,GRAY);text(L+111,y,d,'Helvetica',5.65,GRAY);y-=6.8 Y-=47 Y=para(L,Y,'Other types: GDM, MODY, pancreatic diabetes, endocrinopathies, and drug-induced diabetes (especially glucocorticoids).',colw,6.1,7.25) Y-=4 # Acute Y=section(L,Y,colw,'3. ACUTE COMPLICATIONS') rect(L,Y-39,colw,37,LIGHTRED) text(L+5,Y-10,'DKA','Helvetica-Bold',7,RED) text(L+29,Y-10,'Glucose >250 + ketones + HAGMA', 'Helvetica-Bold',6.2,NAVY) text(L+5,Y-18,'pH <7.30; HCO₃⁻ <18. Often Type 1 / infection / missed insulin.', 'Helvetica',5.9,GRAY) text(L+5,Y-28,'Order: Fluids → K⁺ → IV regular insulin → dextrose at glucose ~200.', 'Helvetica-Bold',5.8,RED) Y-=44 rect(L,Y-25,colw,23,PALE) text(L+5,Y-10,'HHS','Helvetica-Bold',7,GOLD) text(L+29,Y-10,'Type 2; glucose often >600, severe dehydration, high osmolality,', 'Helvetica',5.9,GRAY) text(L+29,Y-18,'minimal ketosis/acidosis, prominent altered sensorium.', 'Helvetica',5.9,GRAY) Y-=31 Y=para(L,Y,'Potassium in DKA: if K⁺ <3.3 mEq/L, replace K⁺ first and withhold insulin.',colw,6.05,7.2,'Helvetica-Bold',RED) Y-=4 # treatments Y=section(L,Y,colw,'4. DRUG PEARLS') items=[ ('Metformin','↓ hepatic gluconeogenesis; GI effects, B12 deficiency; avoid in severe renal dysfunction.'), ('SGLT2 inhibitors','HF/CKD benefit; genital infection, volume depletion, euglycemic DKA.'), ('GLP-1 RAs','Weight loss; GI effects; avoid in MEN2/medullary thyroid carcinoma.'), ('TZDs','Edema, weight gain, fractures; avoid in heart failure.'), ('Sulfonylureas','Hypoglycemia + weight gain.'), ('Insulin','Mandatory in Type 1. Regular insulin is used IV in DKA.')] for lab,body in items: c.setFont('Helvetica-Bold',6.1); c.setFillColor(NAVY); c.drawString(L,Y,'• '+lab) lx=stringWidth('• '+lab,'Helvetica-Bold',6.1) Y=para(L+lx+2,Y,body,colw-lx-2,6.0,7.05) Y-=1 # RIGHT Y=section(R,top,colw,'5. COMPLICATIONS: EXAM FAVOURITES') # micro box rect(R,Y-58,colw,56,PALE) text(R+5,Y-10,'MICROVASCULAR: RNN', 'Helvetica-Bold',6.7,TEAL) text(R+5,Y-19,'Retinopathy','Helvetica-Bold',6.1,NAVY); text(R+48,Y-19,'Earliest lesion = microaneurysm', 'Helvetica',6.1,GRAY) text(R+5,Y-28,'Nephropathy','Helvetica-Bold',6.1,NAVY); text(R+48,Y-28,'UACR 30-300 mg/g = early clinical marker', 'Helvetica',5.75,GRAY) text(R+5,Y-37,'Neuropathy','Helvetica-Bold',6.1,NAVY); text(R+48,Y-37,'Most common: distal symmetric polyneuropathy', 'Helvetica',5.65,GRAY) text(R+5,Y-47,'Renal hallmark','Helvetica-Bold',6.1,NAVY); text(R+48,Y-47,'Kimmelstiel-Wilson nodules', 'Helvetica',6.05,RED) Y-=64 rect(R,Y-25,colw,23,LIGHTBLUE) text(R+5,Y-10,'MACROVASCULAR','Helvetica-Bold',6.5,BLUE) text(R+70,Y-10,'CAD • Stroke • PAD', 'Helvetica-Bold',6.4,NAVY) text(R+5,Y-19,'Most common cause of death: cardiovascular disease.', 'Helvetica',5.9,GRAY) Y-=31 # insulin Y=section(R,Y,colw,'6. INSULIN: MUST REMEMBER') rect(R,Y-37,colw,35,PALE) text(R+5,Y-10,'Rapid','Helvetica-Bold',6.1,NAVY);text(R+38,Y-10,'Lispro, Aspart, Glulisine','Helvetica',6.1,GRAY) text(R+5,Y-18,'Short','Helvetica-Bold',6.1,NAVY);text(R+38,Y-18,'Regular → IV in DKA','Helvetica-Bold',6.1,RED) text(R+5,Y-26,'Intermediate','Helvetica-Bold',6.1,NAVY);text(R+55,Y-26,'NPH → peak / nocturnal hypoglycemia','Helvetica',5.8,GRAY) text(R+5,Y-34,'Long','Helvetica-Bold',6.1,NAVY);text(R+38,Y-34,'Glargine, Detemir, Degludec | Do not mix glargine','Helvetica',5.55,GRAY) Y-=43 # mnemonics Y=section(R,Y,colw,'7. LAST-MINUTE ONE-LINERS') ones=[ '• Anti-GAD: common autoantibody in Type 1 DM.', '• C-peptide: best marker of endogenous insulin secretion.', '• Acanthosis nigricans suggests insulin resistance.', '• DKA = high-anion-gap metabolic acidosis; HHS = high osmolality.', '• Hypoglycemia: adrenergic symptoms first, then neuroglycopenia.', '• ACEi/ARB: albuminuric diabetic kidney disease, especially with HTN.', '• Diabetic foot = neuropathy + ischemia + infection.', '• Most common MODY: HNF1A-MODY; often sulfonylurea responsive.' ] for s in ones: Y=para(R,Y,s,colw,6.05,7.5,'Helvetica',GRAY) Y-=3 rect(R,Y-25,colw,23,HexColor('#FFF6E6')) text(R+5,Y-10,'MEMORY HOOK','Helvetica-Bold',6.4,GOLD) text(R+5,Y-19,'RNN + CVS = Retinopathy, Nephropathy, Neuropathy + CAD, Vascular disease, Stroke', 'Helvetica-Bold',5.75,NAVY) # footer c.setStrokeColor(HexColor('#D5DBDB'));c.line(margin,13,W-margin,13) text(margin,7,'NEET PG Rapid Revision | Educational revision sheet - verify changing clinical guidelines separately.', 'Helvetica',5.5,GRAY) text(W-78,7,'DIABETES • 2026','Helvetica-Bold',5.5,BLUE) c.showPage();c.save() print(out) PY python - <<'PY' from pypdf import PdfReader p='/tmp/workspace/diabetes-rapid-revision/output/Diabetes_NEETPG_Rapid_Revision.pdf' r=PdfReader(p) print('pages=',len(r.pages),'size=',__import__('os').path.getsize(p),'text_chars=',len(r.pages[0].extract_text() or '')) PY

Diabetes NEETPG Rapid Revision

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