Medical Emergencies · patient case with 2 questions
Type 2 diabetes in a patient with a BMI of 30
Patient: Male, 47 years old
Chief Complaint: “My gums bleed and my mouth is always dry.”
Background: Type 2 diabetes mellitus diagnosed three years ago, on metformin. Sedentary desk work. No tobacco.
Vital Signs: BP 138/86 mmHg · HR 78 bpm · BMI 30.4 kg/m² · HbA1c 8.1%
Findings: Generalized moderate periodontitis with bleeding on probing. Reduced salivary flow. No caries.
Question 1
What best explains the development of this patient's diabetes?
Show answer and explanation
Correct answer: D. Peripheral insulin resistance, most often related to chronic obesity
- A. Absolute insulin deficiency from childhood again describes type 1. In type 2 diabetes insulin is present, often in excess early on; the tissues simply do not respond to it.
- B. Type IV hypersensitivity is delayed, T-cell mediated — contact dermatitis, the tuberculin reaction, graft rejection. It has no role in the pathogenesis of type 2 diabetes.
- C. Autoimmune beta-cell destruction, mediated by anti-GAD and islet-cell antibodies, defines TYPE 1 diabetes. It presents typically in childhood or adolescence with weight LOSS, and these patients are insulin-dependent from the outset.
- D. CORRECT. Type 2 diabetes begins as INSULIN RESISTANCE in muscle, liver and adipose tissue. Excess visceral adipose tissue is metabolically active — it releases free fatty acids and inflammatory cytokines (TNF-α, IL-6, resistin) that interfere with insulin receptor signalling. The pancreas compensates with hyperinsulinaemia for years before beta-cell function fails and frank hyperglycaemia appears. A BMI of 30 places him in the obese range, and obesity is the single largest modifiable risk factor.
Note: BMI bands: under 18.5 underweight; 18.5–24.9 normal; 25–29.9 overweight; 30 and above obese, subdivided into class I (30–34.9), class II (35–39.9) and class III (40+).
Question 2
An elevated BMI is most strongly associated with an increased incidence of which malignancies?
Show answer and explanation
Correct answer: A. Colorectal and renal carcinoma
- A. CORRECT. Obesity is an established risk factor for at least thirteen cancers, and COLORECTAL and RENAL (kidney) carcinoma are among the best characterised. The mechanisms are chronic hyperinsulinaemia and raised IGF-1 signalling, which promote cell proliferation and inhibit apoptosis; adipose-derived oestrogen; and low-grade systemic inflammation. Others in the group include endometrial, postmenopausal breast, oesophageal adenocarcinoma, gastric cardia, liver, gallbladder, pancreatic, ovarian, thyroid, meningioma and multiple myeloma.
- B. Retinoblastoma is a childhood tumour driven by biallelic RB1 loss, and optic nerve glioma is associated with neurofibromatosis type 1. Neither has a metabolic risk association.
- C. Acute lymphoblastic leukaemia is a childhood malignancy with genetic and environmental associations unrelated to adult adiposity.
- D. Basal cell carcinoma is driven overwhelmingly by cumulative ultraviolet exposure and by fair skin phototype, not by body mass.
Note: The dental relevance runs the other way as well: obesity and type 2 diabetes are independently associated with more severe periodontitis, and the relationship is bidirectional — treating periodontitis produces a small but measurable fall in HbA1c.