diff --git a/lib/client/careportal.js b/lib/client/careportal.js
index 0d1220d55a7..a5c86232d8e 100644
--- a/lib/client/careportal.js
+++ b/lib/client/careportal.js
@@ -4,6 +4,7 @@ var moment = require('moment-timezone');
 var _ = require('lodash');
 var parse_duration = require('parse-duration'); // https://www.npmjs.com/package/parse-duration
 var times = require('../times');
+var consts = require('../constants');
 var Storages = require('js-storage');
 
 function init (client, $) {
@@ -240,8 +241,8 @@ function init (client, $) {
     }
 
     if (units == "mmol") {
-      data.targetTop = data.targetTop * 18;
-      data.targetBottom = data.targetBottom * 18;
+      data.targetTop = data.targetTop * consts.MMOL_TO_MGDL;
+      data.targetBottom = data.targetBottom * consts.MMOL_TO_MGDL;
     }
 
     //special handling for absolute to support temp to 0
@@ -298,14 +299,14 @@ function init (client, $) {
         let targetTop = parseInt(data.targetTop);
         let targetBottom = parseInt(data.targetBottom);
 
-        let minTarget = 4 * 18;
-        let maxTarget = 18 * 18;
+        let minTarget = 4 * consts.MMOL_TO_MGDL;
+        let maxTarget = 18 * consts.MMOL_TO_MGDL;
 
         if (units == "mmol") {
-          targetTop = Math.round(targetTop / 18.0 * 10) / 10;
-          targetBottom = Math.round(targetBottom / 18.0 * 10) / 10;
-          minTarget = Math.round(minTarget / 18.0 * 10) / 10;
-          maxTarget = Math.round(maxTarget / 18.0 * 10) / 10;
+          targetTop = Math.round(targetTop / consts.MMOL_TO_MGDL * 10) / 10;
+          targetBottom = Math.round(targetBottom / consts.MMOL_TO_MGDL * 10) / 10;
+          minTarget = Math.round(minTarget / consts.MMOL_TO_MGDL * 10) / 10;
+          maxTarget = Math.round(maxTarget / consts.MMOL_TO_MGDL * 10) / 10;
         }
 
         if (targetTop > maxTarget) {
@@ -358,8 +359,8 @@ function init (client, $) {
     var targetBottom = data.targetBottom;
 
     if (units == "mmol") {
-      targetTop = Math.round(data.targetTop / 18.0 * 10) / 10;
-      targetBottom = Math.round(data.targetBottom / 18.0 * 10) / 10;
+      targetTop = Math.round(data.targetTop / consts.MMOL_TO_MGDL * 10) / 10;
+      targetBottom = Math.round(data.targetBottom / consts.MMOL_TO_MGDL * 10) / 10;
     }
 
     pushIf(data.targetTop, translate('Target Top') + ': ' + targetTop);
diff --git a/lib/client/renderer.js b/lib/client/renderer.js
index 688b046b7b2..5a0354afc51 100644
--- a/lib/client/renderer.js
+++ b/lib/client/renderer.js
@@ -2,6 +2,7 @@
 
 var _ = require('lodash');
 var times = require('../times');
+var consts = require('../constants');
 
 var DEFAULT_FOCUS = times.hours(3).msecs
   , WIDTH_SMALL_DOTS = 420
@@ -210,8 +211,8 @@ function init (client, d3) {
       var targetTop = d.targetTop;
 
       if (client.settings.units === 'mmol') {
-        targetBottom = Math.round(targetBottom / 18.0 * 10) / 10;
-        targetTop = Math.round(targetTop / 18.0 * 10) / 10;
+        targetBottom = Math.round(targetBottom / consts.MMOL_TO_MGDL * 10) / 10;
+        targetTop = Math.round(targetTop / consts.MMOL_TO_MGDL * 10) / 10;
       }
 
       var correctionRangeText;
@@ -632,7 +633,7 @@ function init (client, d3) {
     function treatmentTooltip () {
       var glucose = treatment.glucose;
       if (client.settings.units != client.ddata.profile.getUnits()) {
-        glucose *= (client.settings.units === 'mmol' ? 0.055 : 18);
+        glucose *= (client.settings.units === 'mmol' ? (1 / consts.MMOL_TO_MGDL) : consts.MMOL_TO_MGDL);
         var decimals = (client.settings.units === 'mmol' ? 10 : 1);
 
         glucose = Math.round(glucose * decimals) / decimals;
diff --git a/lib/constants.json b/lib/constants.json
index 31a4524b4d3..c2736f7e6e9 100644
--- a/lib/constants.json
+++ b/lib/constants.json
@@ -4,5 +4,6 @@
   "HTTP_UNAUTHORIZED" : 401,
   "HTTP_VALIDATION_ERROR" : 422,
   "HTTP_INTERNAL_ERROR" : 500,
-  "ENTRIES_DEFAULT_COUNT" : 10
+  "ENTRIES_DEFAULT_COUNT" : 10,
+  "MMOL_TO_MGDL": 18
 }
diff --git a/lib/data/ddata.js b/lib/data/ddata.js
index 0251ec17d99..9fa470e3f16 100644
--- a/lib/data/ddata.js
+++ b/lib/data/ddata.js
@@ -2,6 +2,7 @@
 
 var _ = require('lodash');
 var times = require('../times');
+var consts = require('../constants');
 
 var DEVICE_TYPE_FIELDS = ['uploader', 'pump', 'openaps', 'loop', 'xdripjs'];
 
@@ -213,18 +214,18 @@ function init () {
       if (t.units) {
         if (t.units == 'mmol') {
           //convert to mgdl
-          t.targetTop = t.targetTop * 18;
-          t.targetBottom = t.targetBottom * 18;
+          t.targetTop = t.targetTop * consts.MMOL_TO_MGDL;
+          t.targetBottom = t.targetBottom * consts.MMOL_TO_MGDL;
           t.units = 'mg/dl';
         }
       }
       //if we have a temp target thats below 20, assume its mmol and convert to mgdl for safety.
       if (t.targetTop < 20) {
-        t.targetTop = t.targetTop * 18;
+        t.targetTop = t.targetTop * consts.MMOL_TO_MGDL;
         t.units = 'mg/dl';
       }
       if (t.targetBottom < 20) {
-        t.targetBottom = t.targetBottom * 18;
+        t.targetBottom = t.targetBottom * consts.MMOL_TO_MGDL;
         t.units = 'mg/dl';
       }
       return t.eventType && t.eventType.indexOf('Temporary Target') > -1;
diff --git a/lib/data/treatmenttocurve.js b/lib/data/treatmenttocurve.js
index 8bca564d091..afa17b397ec 100644
--- a/lib/data/treatmenttocurve.js
+++ b/lib/data/treatmenttocurve.js
@@ -1,9 +1,10 @@
 'use strict';
 
 var _ = require('lodash');
+var consts = require('../constants');
 
 const MAX_BG_MMOL = 22;
-const MAX_BG_MGDL = MAX_BG_MMOL * 18;
+const MAX_BG_MGDL = MAX_BG_MMOL * consts.MMOL_TO_MGDL;
 
 module.exports = function fitTreatmentsToBGCurve (ddata, env, ctx) {
 
diff --git a/lib/plugins/basalprofile.js b/lib/plugins/basalprofile.js
index 73c9492ea44..a766f9ab0a8 100644
--- a/lib/plugins/basalprofile.js
+++ b/lib/plugins/basalprofile.js
@@ -1,6 +1,7 @@
 'use strict';
 var times = require('../times');
 var moment = require('moment');
+var consts = require('../constants');
 
 function init (ctx) {
 
@@ -65,7 +66,7 @@ function init (ctx) {
     var units = profile.getUnits();
 
     if (sbx.settings.units != units) {
-      sensitivity *= (sbx.settings.units === 'mmol' ? 0.055 : 18);
+      sensitivity *= (sbx.settings.units === 'mmol' ? (1 / consts.MMOL_TO_MGDL) : consts.MMOL_TO_MGDL);
       var decimals = (sbx.settings.units === 'mmol' ? 10 : 1);
 
       sensitivity = Math.round(sensitivity * decimals) / decimals;
diff --git a/lib/plugins/openaps.js b/lib/plugins/openaps.js
index 77f27288b14..4d2535a3b76 100644
--- a/lib/plugins/openaps.js
+++ b/lib/plugins/openaps.js
@@ -4,6 +4,7 @@ var _ = require('lodash');
 var moment = require('moment');
 var times = require('../times');
 var levels = require('../levels');
+var consts = require('../constants');
 
 // var ALL_STATUS_FIELDS = ['status-symbol', 'status-label', 'iob', 'meal-assist', 'freq', 'rssi']; Unused variable
 
@@ -352,7 +353,7 @@ function init (ctx) {
         var units = sbx.data.profile.getUnits();
 
         if (units === 'mmol') {
-          bg = Math.round(bg / 18 * 10) / 10;
+          bg = Math.round(bg / consts.MMOL_TO_MGDL * 10) / 10;
         }
 
         var valueParts = [
diff --git a/lib/report_plugins/glucosedistribution.js b/lib/report_plugins/glucosedistribution.js
index 3d8d109610b..2d034d2bba8 100644
--- a/lib/report_plugins/glucosedistribution.js
+++ b/lib/report_plugins/glucosedistribution.js
@@ -1,5 +1,7 @@
 'use strict';
 
+var consts = require('../constants');
+
 var glucosedistribution = {
   name: 'glucosedistribution'
   , label: 'Distribution'
@@ -174,7 +176,7 @@ glucosedistribution.report = function report_glucosedistribution (datastorage, s
       var bg = Math.floor(entry.bgValue + bgDelta * j);
       var t = new Date(entry.displayTime.getTime() + j * timePatch);
       var newEntry = {
-        sgv: displayUnits === 'mmol' ? bg / 18 : bg
+        sgv: displayUnits === 'mmol' ? bg / consts.MMOL_TO_MGDL : bg
         , bgValue: bg
         , displayTime: t
       };
@@ -217,7 +219,7 @@ glucosedistribution.report = function report_glucosedistribution (datastorage, s
       const interpolatedValue = prevEntry.bgValue + d;
 
       let newEntry = {
-        sgv: displayUnits === 'mmol' ? interpolatedValue / 18 : interpolatedValue
+        sgv: displayUnits === 'mmol' ? interpolatedValue / consts.MMOL_TO_MGDL : interpolatedValue
         , bgValue: interpolatedValue
         , displayTime: entry.displayTime
       };
@@ -433,11 +435,11 @@ glucosedistribution.report = function report_glucosedistribution (datastorage, s
 
   var unitString = ' mg/dl';
   if (displayUnits == 'mmol') {
-    TDC = TDC / 18.0;
-    TDCHourly = TDCHourly / 18.0;
+    TDC = TDC / consts.MMOL_TO_MGDL;
+    TDCHourly = TDCHourly / consts.MMOL_TO_MGDL;
     unitString = ' mmol/L';
 
-    RMS = Math.sqrt(RMSTotal / events) / 18;
+    RMS = Math.sqrt(RMSTotal / events) / consts.MMOL_TO_MGDL;
   }
 
   TDC = Math.round(TDC * 100) / 100;
diff --git a/lib/report_plugins/utils.js b/lib/report_plugins/utils.js
index 10daec32304..be6ba940003 100644
--- a/lib/report_plugins/utils.js
+++ b/lib/report_plugins/utils.js
@@ -1,5 +1,7 @@
 'use strict';
 
+var consts = require('../constants');
+
 var moment = window.moment;
 var utils = { };
 
@@ -69,7 +71,7 @@ utils.scaledTreatmentBG = function scaledTreatmentBG(treatment,data) {
         console.info('found mismatched glucose units, converting ' + treatment.units + ' into ' + client.settings.units, treatment);
         if (treatment.units === 'mmol') {
           //BG is in mmol and display in mg/dl
-          treatmentGlucose = Math.round(treatment.glucose * 18);
+          treatmentGlucose = Math.round(treatment.glucose * consts.MMOL_TO_MGDL);
         } else {
           //BG is in mg/dl and display in mmol
           treatmentGlucose = client.utils.scaleMgdl(treatment.glucose);
diff --git a/lib/units.js b/lib/units.js
index f548d55744e..5eb36c10950 100644
--- a/lib/units.js
+++ b/lib/units.js
@@ -1,11 +1,13 @@
 'use strict';
 
+var consts = require('./constants');
+
 function mgdlToMMOL(mgdl) {
-  return (Math.round((mgdl / 18) * 10) / 10).toFixed(1);
+  return (Math.round((mgdl / consts.MMOL_TO_MGDL) * 10) / 10).toFixed(1);
 }
 
 function mmolToMgdl(mgdl) {
-  return Math.round(mgdl * 18);
+  return Math.round(mgdl * consts.MMOL_TO_MGDL);
 }
 
 function configure() {