Diabetes mellitus: types, symptoms, metabolic changes and complications
Diabetes is chronic high blood sugar from too little insulin or insulin that does not work. It upsets carbohydrate, fat and protein metabolism and damages eyes, kidneys, nerves and heart.
At a glance
Types of diabetes
| Type | Cause | Who and how | Treatment |
|---|---|---|---|
| Type 1 | Autoimmune destruction of insulin-making beta cells: absolute insulin lack | Usually children and young adults; thin; sudden onset; prone to ketoacidosis | Insulin for life, diet matched to insulin |
| Type 2 | Insulin resistance with relative insulin lack | Mostly adults, now younger in India; often overweight with a large waist; slow onset; family history | Diet, exercise, tablets; insulin if needed |
| Gestational (GDM) | High blood sugar first found in pregnancy, from pregnancy hormones | Pregnant women; raises later risk of type 2 in mother and child | Diet, activity, insulin or tablets if needed |
| Other specific types | Single-gene diabetes (MODY), pancreatic disease (including fibrocalculous pancreatic diabetes seen in India), drugs such as steroids | Depends on cause | Treat the cause; diet and drugs |
Draw it: how symptoms arise
Metabolic changes
| Metabolism | What happens | Result |
|---|---|---|
| Carbohydrate | Less glucose taken up by muscle and fat; less glycogen made; more glycogen breakdown and gluconeogenesis in the liver | Hyperglycaemia and glycosuria |
| Fat | More fat breakdown (lipolysis); excess fatty acids turned into ketone bodies in the liver | High triglycerides; ketosis and ketoacidosis, mainly in type 1 |
| Protein | More protein breakdown, less protein made; amino acids used to make glucose | Muscle wasting, weight loss, negative nitrogen balance, slow healing |
| Water and electrolytes | Glucose in urine pulls water and salts out | Polyuria, dehydration, loss of sodium and potassium, thirst |
Complications and the role of diet
| Complication | What it is | Diet and care |
|---|---|---|
| Hypoglycaemia (acute) | Blood glucose below 70 mg/dL: sweating, shaking, confusion; from missed meals, extra insulin or exercise | 15-15 rule: take 15 g quick sugar (3 level teaspoons of sugar or glucose in water, or ½ cup, about 120 mL, of fruit juice), recheck after 15 minutes; then a snack |
| Diabetic ketoacidosis (acute) | Very high sugar with ketones; vomiting, deep breathing; mainly type 1 | Hospital: fluids, insulin, potassium; then gradual return to diet |
| Hyperosmolar state (acute) | Very high sugar and severe dehydration without much ketosis; older type 2 patients | Hospital fluids and insulin |
| Microvascular (chronic) | Retinopathy (eyes), nephropathy (kidneys), neuropathy (nerves), diabetic foot | Good sugar and blood pressure control; protein 0.8 g/kg in kidney disease not on dialysis (ADA, KDIGO); less salt; foot care |
| Macrovascular (chronic) | Heart attack, stroke, poor circulation in legs | Low saturated and trans fat, high fibre, salt under 5 g, no smoking, weight control |
On the ward, check sugar before each meal and make sure insulin and the food tray arrive together. Every diabetic patient and family should learn the 15-15 rule before going home.
2 marks: “Differentiate type 1 and type 2 diabetes.” Type 1: autoimmune loss of beta cells, absolute insulin lack, young and thin, needs insulin. Type 2: insulin resistance, adults, often obese, managed with diet, exercise and tablets.
5 marks: “Explain the metabolic changes in diabetes mellitus.” Carbohydrate (hyperglycaemia, glycosuria), fat (lipolysis, ketones, high TG), protein (breakdown, wasting), water and electrolytes (polyuria, dehydration).
10 marks: “Define diabetes mellitus. Discuss its types, symptoms, metabolic changes and complications.” Definition and diagnosis, types table, symptoms with flow diagram, metabolic changes table, acute and chronic complications with diet role.
Three Ps: Polyuria, Polydipsia, Polyphagia. Diagnosis numbers: 126 fasting, 200 after glucose, 6.5% HbA1c.