UPPSC 2021 Prelims GS Paper-I · Question 90 of 150

Correct — B, Milligram per decilitre (mg/dL). In clinical and laboratory practice blood glucose (blood sugar) is reported as milligrams of glucose per decilitre of blood; a normal fasting value is roughly 70-99 mg/dL. (The SI alternative used in many countries is millimoles per litre, mmol/L, but among the four options given, mg/dL is the standard expression.) Hence option (b) is correct.

• (a)MM of Hg — Wrong — millimetres of mercury (mm Hg) is a unit of PRESSURE (e.g. blood pressure, gas partial pressures), not of a dissolved substance's concentration like glucose.
• (c)Parts per million — Wrong — parts per million (ppm) is used for very dilute/trace concentrations (e.g. pollutants, water hardness), not for the routine reporting of blood glucose.
• (d)Gram per litre — Wrong — grams per litre is not the conventional clinical unit for blood glucose; laboratories report it in milligrams per decilitre (mg/dL), the smaller, standard unit.

Blood glucose is the concentration of glucose (the body's main circulating sugar) in the blood, kept within a narrow range by the hormones insulin and glucagon. It is conventionally measured in milligrams per decilitre (mg/dL). Typical reference values: fasting about 70-99 mg/dL, with 100-125 mg/dL flagged as pre-diabetic and >=126 mg/dL (fasting) indicating diabetes. The SI unit millimoles per litre (mmol/L) is used in some countries, but Indian and US reports use mg/dL.

Match the quantity to the right kind of unit. Glucose is a solute, so its amount is expressed as a mass-per-volume concentration — mg/dL. mm Hg measures pressure (a distractor borrowed from blood-pressure readings), ppm is for trace amounts, and g/L is not the standard clinical unit. That reasoning isolates mg/dL, option (b).

• Blood glucose is reported in milligrams per decilitre (mg/dL); the SI alternative is mmol/L.
• Normal fasting blood glucose is about 70-99 mg/dL.
• mm Hg is a unit of pressure (blood pressure), not concentration.
• Blood glucose is regulated by insulin (lowers it) and glucagon (raises it).

• Picking 'mm of Hg' by association with blood-pressure readings — that is a pressure unit, not a concentration
• Confusing ppm (trace-level unit) or g/L with the standard clinical mg/dL

UPSC/UPPSC ask units-and-measurement and human-physiology items — link each quantity to its unit (glucose = mg/dL, blood pressure = mm Hg) and know the hormones/organs that regulate blood sugar.

• practice — not a real PYQ

  Which hormone lowers the blood glucose level in the human body?

  • (a)Glucagon
  • (b)Insulin
  • (c)Adrenaline
  • (d)Thyroxine

  Answer(b) Insulin — secreted by the beta cells of the Islets of Langerhans in the pancreas, insulin lowers blood glucose; glucagon raises it.

• practice — not a real PYQ

  The unit 'millimetre of mercury (mm Hg)' is commonly used to express which of the following?

  • (a)Blood glucose level
  • (b)Blood pressure
  • (c)Body temperature
  • (d)Haemoglobin content

  Answer(b) Blood pressure — mm Hg is a pressure unit used for blood pressure; blood glucose is expressed in mg/dL.