In an observational study, among 550 type 2 diabetespatients using metformin, cobalamin and holotranscobalamin (holoTCII) levels were measured at the annual diabetes checkup, and deficiencies were defined as <148 and <21 pmol/L, respectively. Depression and cognitive function were assessed with corresponding International Classification of Primary Care codes and questionnaires; neuropathy with medical record data and a questionnaire. Confounding variables were retrieved from medical records. Multivariable logistic and linear regressions were used with cobalamin status as independent variable; depression, cognition and neuropathy as dependent variables.
The mean duration of diabetes was 8.4 years (±5.8); mean duration of metformin use was 64.1 months (±43.2), with a meanmetformindose of 1,306 mg/day. A sufficient cobalamin level was independently associated with a decreasedrisk of depression (OR 0.42; 95 % CI 0.23-0.78) and better cognitiveperformance (β = 1.79; 95 % CI 0.07-3.52) adjusted for confounders. This indicates that cobalamin-deficient patients had a 2.4 times higher chance of depression and a 1.79 point lowercognitiveperformance score. HoloTCII was not associated with any outcome.
CONCLUSIONS: Cobalamin deficiency was associated with an increasedrisk of depression and worse cognitiveperformance, while holoTCII was not. Screening for cobalamin deficiency may be warranted in diabetespatients using metformin. Physicians should consider a cobalamin deficiency in diabetespatients using metformin with a depression or cognitive decline."
Strong Magnitude of Effect.
Comments:cobalamin-deficient patients had a 2.4 times higher chance of depression and a 1.79 point lowercognitiveperformance score
serum markers of vitamin B12 status were related to summary measures of neuropsychological tests of 5 cognitive domains and brain MRI measures obtained on average 4.6 years later among 121 older adults.
"A doubling in holoTC concentrations (from 50 to 100 pmol/L) was associated with a 30% slower rate of cognitive decline (-0.137 to -0.083), whereas a doubling in tHcy (from 10 to 20 micromol/L) or MMA (from 0.25 to 0.50 micromol/L) was associated with >50% more rapid cognitive decline (-0.090 to -0.169) and (-0.104 to -0.169), respectively. After adjustment for all vitamin markers simultaneously, the associations of cognitive decline with holoTC and MMA remained significant."