IM11.11-13 | Diabetes Diagnostic Testing — Summary & Reflection

KEY TAKEAWAYS

Diabetes diagnostic testing spans three competency levels. (1) Laboratory panel (IM11.11): FPG ≥126 mg/dL; 2-h OGTT ≥200; HbA1c ≥6.5% (unreliable in haemolytic anaemia, haemoglobinopathies, iron deficiency); random glucose ≥200 with symptoms — any one confirmed on repeat = diabetes. Complication monitoring: ACR (microalbuminuria 3–30 mg/mmol = early nephropathy), eGFR (CKD staging), fasting lipids (LDL target <2.6 or <1.8 if CVD), electrolytes (K+ before insulin in DKA), ABG (HAGMA in DKA: pH <7.3, HCO₃ <18, anion gap >12). (2) Capillary blood glucose (IM11.12): Use lateral fingertip; dry after alcohol wipe; gentle proximal pressure (no squeezing); not diagnostic (±15–20% error); CBG lags during rapidly changing glucose. (3) Urinary ketone dipstick (IM11.13): Nitroprusside reaction detects acetoacetate and acetone — NOT beta-hydroxybutyrate; read at 40–60 seconds; in DKA treatment, urine ketones may appear worse as BHB converts to acetoacetate; blood BHB is superior for monitoring. Key K+ rule in DKA: K+ <3.5 mEq/L → hold insulin until replaced.

REFLECT

You began this module with two scenarios: one where a simple HbA1c and fasting glucose needed to be reconciled into a diagnosis, and one where a glucometer and a urine dipstick strip would guide an emergency decision at midnight. Think about both again: the first requires you to know not just the thresholds but the conditions under which each test is and is not reliable — and the HbA1c reliability limitations are the most commonly missed question in this area. The second requires you to act on a bedside test with the understanding of what it cannot tell you — specifically, that a urine dipstick negative for ketones does not rule out DKA if beta-hydroxybutyrate predominates. The gap between knowing a test's reference range and knowing its limitations is the gap between passing an examination and keeping a patient safe. This module has tried to close that gap.